diff --git a/glsm/src/main/java/com/gtnewhorizons/angelica/glsm/backend/MainThreadPump.java b/glsm/src/main/java/com/gtnewhorizons/angelica/glsm/backend/MainThreadPump.java
index c0508a4d0..afe2c1cef 100644
--- a/glsm/src/main/java/com/gtnewhorizons/angelica/glsm/backend/MainThreadPump.java
+++ b/glsm/src/main/java/com/gtnewhorizons/angelica/glsm/backend/MainThreadPump.java
@@ -34,6 +34,11 @@ public final class MainThreadPump {
     private Throwable failure;
     private ClassLoader callerLoader;
 
+    private boolean presentPumpPending;
+    private boolean presentInFlight;
+    private Throwable presentFailure;
+    private ClassLoader presentLoader;
+
     public MainThreadPump(Executor mainExecutor, BooleanSupplier isMainThread, Runnable pumpBody, Runnable pollBody) {
         this.mainExecutor = mainExecutor;
         this.isMainThread = isMainThread;
@@ -48,7 +53,11 @@ public final class MainThreadPump {
                 pumpBody.run();
             } else {
                 synchronized (lock) {
-                    runPumpOnMainThread();
+                    await(true);
+                    final Throwable t = presentFailure;
+                    presentFailure = null;
+                    if (t != null) throw asUnchecked(t);
+                    if (!presentInFlight) runPumpOnMainThread();
                 }
             }
             pollBody.run();
@@ -60,47 +69,86 @@ public final class MainThreadPump {
     private void runPumpOnMainThread() {
         final Thread self = Thread.currentThread();
         callerLoader = self.getContextClassLoader();
-        failure = null;
         done = false;
         mainExecutor.execute(task);
-        boolean interrupted = false;
-        boolean stallReported = false;
-        final long stallAt = System.nanoTime() + STALL_WARN_NANOS;
-        while (!done) {
-            try {
-                lock.wait(PARK_MILLIS);
-            } catch (InterruptedException e) {
-                interrupted = true;
-            }
-            if (!done && !stallReported && System.nanoTime() - stallAt >= 0L) {
-                stallReported = true;
-                LOGGER.warn("Display message pump has been waiting on the RFB main thread for over {} ms", STALL_WARN_NANOS / 1_000_000L);
-            }
-        }
-        if (interrupted) self.interrupt();
+        await(false);
         final Throwable t = failure;
         if (t != null) {
             throw asUnchecked(t);
         }
     }
 
+    private boolean waiting(boolean presentPump) {
+        return presentPump ? presentPumpPending : !done;
+    }
+
+    private void await(boolean presentPump) {
+        boolean interrupted = false;
+        boolean stallReported = false;
+        final long stallAt = System.nanoTime() + STALL_WARN_NANOS;
+        while (waiting(presentPump)) {
+            try {
+                lock.wait(PARK_MILLIS);
+            } catch (InterruptedException e) {
+                interrupted = true;
+            }
+            if (waiting(presentPump) && !stallReported && System.nanoTime() - stallAt >= 0L) {
+                stallReported = true;
+                LOGGER.warn("Display message pump has been waiting on the RFB main thread for over {} ms", STALL_WARN_NANOS / 1_000_000L);
+            }
+        }
+        if (interrupted) Thread.currentThread().interrupt();
+    }
+
+    public void beginPresent() {
+        synchronized (lock) {
+            presentInFlight = true;
+            presentPumpPending = true;
+            presentLoader = Thread.currentThread().getContextClassLoader();
+        }
+    }
+
+    public void runPresentPump() {
+        final ClassLoader loader;
+        synchronized (lock) {
+            loader = presentLoader;
+        }
+        final Throwable t = pumpWith(loader);
+        synchronized (lock) {
+            if (t != null) presentFailure = t;
+            presentPumpPending = false;
+            lock.notifyAll();
+        }
+    }
+
+    public void endPresent() {
+        synchronized (lock) {
+            presentInFlight = false;
+            presentPumpPending = false;
+            lock.notifyAll();
+        }
+    }
+
     private void runPump() {
+        final Throwable t = pumpWith(callerLoader);
+        synchronized (lock) {
+            failure = t;
+            done = true;
+            lock.notifyAll();
+        }
+    }
+
+    private Throwable pumpWith(ClassLoader loader) {
         final Thread self = Thread.currentThread();
         final ClassLoader saved = self.getContextClassLoader();
         try {
-            self.setContextClassLoader(callerLoader);
+            if (loader != null) self.setContextClassLoader(loader);
             pumpBody.run();
+            return null;
         } catch (Throwable t) {
-            failure = t;
+            return t;
         } finally {
-            try {
-                self.setContextClassLoader(saved);
-            } finally {
-                synchronized (lock) {
-                    done = true;
-                    lock.notifyAll();
-                }
-            }
+            self.setContextClassLoader(saved);
         }
     }
 
diff --git a/glsm/src/main/java/com/gtnewhorizons/angelica/glsm/profiling/DebugCounters.java b/glsm/src/main/java/com/gtnewhorizons/angelica/glsm/profiling/DebugCounters.java
new file mode 100644
index 000000000..2336453d2
--- /dev/null
+++ b/glsm/src/main/java/com/gtnewhorizons/angelica/glsm/profiling/DebugCounters.java
@@ -0,0 +1,12 @@
+package com.gtnewhorizons.angelica.glsm.profiling;
+
+import java.util.concurrent.atomic.LongAdder;
+
+public final class DebugCounters {
+    public static final LongAdder FENCE_WAIT_NANOS = new LongAdder();
+    public static final LongAdder TRANSFER_WAIT_NANOS = new LongAdder();
+    public static final LongAdder PRESENTS = new LongAdder();
+    public static final LongAdder EMPTY_ACQUIRES = new LongAdder();
+
+    private DebugCounters() {}
+}
diff --git a/glsm/src/test/java/com/gtnewhorizons/angelica/glsm/backend/MainThreadPumpTest.java b/glsm/src/test/java/com/gtnewhorizons/angelica/glsm/backend/MainThreadPumpTest.java
index 8434ff575..2355611b8 100644
--- a/glsm/src/test/java/com/gtnewhorizons/angelica/glsm/backend/MainThreadPumpTest.java
+++ b/glsm/src/test/java/com/gtnewhorizons/angelica/glsm/backend/MainThreadPumpTest.java
@@ -150,4 +150,75 @@ class MainThreadPumpTest {
         caller.join();
         assertEquals(1, stillInterrupted.get());
     }
+
+    @Test
+    void aClientPumpWaitsForAPendingPresentPumpWithoutEnqueueing() throws Exception {
+        final DeferredExecutor executor = new DeferredExecutor();
+        final AtomicInteger pumps = new AtomicInteger();
+        final AtomicInteger polls = new AtomicInteger();
+        final MainThreadPump p = pump(executor, pumps::incrementAndGet, polls::incrementAndGet);
+
+        p.beginPresent();
+        final Thread caller = new Thread(p::pumpMessages, "pump-caller");
+        caller.start();
+        awaitWaiting(caller);
+        assertTrue(executor.tasks.isEmpty(), "no pump may queue behind an in-flight present");
+
+        p.runPresentPump();
+        caller.join();
+        assertEquals(1, pumps.get());
+        assertEquals(1, polls.get());
+        assertTrue(executor.tasks.isEmpty());
+    }
+
+    @Test
+    void aClientPumpDuringAPresentAfterItsPumpReturnsImmediatelyAndStillPolls() {
+        final DeferredExecutor executor = new DeferredExecutor();
+        final AtomicInteger pumps = new AtomicInteger();
+        final AtomicInteger polls = new AtomicInteger();
+        final MainThreadPump p = pump(executor, pumps::incrementAndGet, polls::incrementAndGet);
+
+        p.beginPresent();
+        p.runPresentPump();
+        p.pumpMessages();
+        p.pumpMessages();
+
+        assertTrue(executor.tasks.isEmpty());
+        assertEquals(1, pumps.get());
+        assertEquals(2, polls.get());
+    }
+
+    @Test
+    void afterEndPresentAClientPumpUsesTheMainThreadAgain() {
+        final InlineExecutor executor = new InlineExecutor();
+        final AtomicInteger pumps = new AtomicInteger();
+        final MainThreadPump p = pump(executor, pumps::incrementAndGet, () -> {});
+
+        p.beginPresent();
+        p.runPresentPump();
+        p.endPresent();
+        p.pumpMessages();
+
+        assertEquals(1, executor.submitted.size());
+        assertEquals(2, pumps.get());
+    }
+
+    @Test
+    void aPresentPumpFailureIsThrownToTheNextClientPumpExactlyOnce() {
+        final InlineExecutor executor = new InlineExecutor();
+        final AtomicInteger pumps = new AtomicInteger();
+        final MainThreadPump p = pump(executor, () -> {
+            if (pumps.incrementAndGet() == 1) throw new IllegalStateException("present boom");
+        }, () -> {});
+
+        p.beginPresent();
+        p.runPresentPump();
+        final IllegalStateException thrown = assertThrows(IllegalStateException.class, p::pumpMessages);
+        assertEquals("present boom", thrown.getMessage());
+
+        p.pumpMessages();
+        p.endPresent();
+        p.pumpMessages();
+        assertEquals(2, pumps.get());
+    }
 }
diff --git a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/SDLGPURenderBackend.java b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/SDLGPURenderBackend.java
index c00e3451d..4de47fc3a 100644
--- a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/SDLGPURenderBackend.java
+++ b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/SDLGPURenderBackend.java
@@ -62,6 +62,7 @@ import com.gtnewhorizons.angelica.sdlgpu.util.ThreadRegistry;
 
 import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;
 import it.unimi.dsi.fastutil.ints.IntOpenHashSet;
+import it.unimi.dsi.fastutil.longs.LongArrayFIFOQueue;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -143,6 +144,7 @@ public class SDLGPURenderBackend extends RenderBackend {
 
 
     private final FenceTracker fenceTracker = new FenceTracker(device, frameManager);
+    private final LongArrayFIFOQueue frameSyncs = new LongArrayFIFOQueue();
     private final FBOClearTracker fboClearTracker = new FBOClearTracker(frameManager, resourceManager, shaderManager);
     private final SamplerBinder samplerBinder = new SamplerBinder(device, resourceManager, shaderManager);
     private final StorageTextureBinder storageTextureBinder = new StorageTextureBinder(resourceManager, shaderManager);
@@ -331,7 +333,7 @@ public class SDLGPURenderBackend extends RenderBackend {
         fenceTracker.setUnresolvedFenceFlush(this::midFrameFenceFlush);
         frameManager.setMainThread(GLStateManager.getMainThread());
         if (!SystemProperties.DISABLE_SDL_PRESENTER_THREAD) {
-            presenter = new Presenter(frameManager, MainStartOnFirstThread.instance());
+            presenter = new Presenter(frameManager, MainStartOnFirstThread.instance(), Pump.INSTANCE);
             frameManager.setPresenter(presenter);
             LOG.info("SDL presenter thread enabled: presents run on '{}'", device.getWindowThread() != null ? device.getWindowThread().getName() : "window thread");
         }
@@ -488,6 +490,7 @@ public class SDLGPURenderBackend extends RenderBackend {
         SDL_WaitForGPUIdle(dev);
         frameManager.endFrame();
         readbackShadows.dispose();
+        frameSyncs.clear();
         fenceTracker.dispose();
         frameManager.releaseAllRegisteredFrames();
         resourceManager.shutdownTexSamplerStates();
@@ -714,7 +717,7 @@ public class SDLGPURenderBackend extends RenderBackend {
     private void drainDeferredPersistentRegions(ContextState st) {
         if (!st.deferUploads) return;
         st.drawsSincePersistentDrain = 0;
-        persistentSync.enqueueDirtyPersistentRegions();
+        if (persistentSync.enqueueDirtyPersistentRegions() > 0) wakeTransferThread();
     }
 
     private void awaitUploadFlush() {
@@ -733,8 +736,8 @@ public class SDLGPURenderBackend extends RenderBackend {
 
     @Override public void onFrameEnd() {
         if (shutdown) return;
-        requestUploadFlush();
         endFrameUploadFlushNoWait();
+        requestUploadFlush();
 
         final FrameState f = frameManager.frame();
         if (f.frameActive && !f.fbo0UsedThisFrame) {
@@ -748,9 +751,19 @@ public class SDLGPURenderBackend extends RenderBackend {
         if (f.frameActive) fboClearTracker.materializeAllPendingClears(s());
         awaitUploadFlush();
         if (SystemProperties.FFP_TRACE) ffpTrace.frameEnd(f);
+        final long frameSync = f.frameActive ? fenceTracker.fenceSync() : 0L;
         frameManager.endFrame();
         frameManager.presentFinalTarget();
         fenceTracker.resolvePendingFences();
+        device.fenceReleaser().drain();
+        if (frameSync != 0L) {
+            frameSyncs.enqueue(frameSync);
+            while (frameSyncs.size() > Device.MAX_FRAMES_IN_FLIGHT - 1) {
+                final long sync = frameSyncs.dequeueLong();
+                fenceTracker.clientWaitSync(sync, 0, Long.MAX_VALUE);
+                fenceTracker.deleteSync(sync);
+            }
+        }
         resourceManager.flushDeferredReleases();
         resourceManager.recycleGpuBufferPool(frameManager.getFrameNumber());
     }
@@ -1777,34 +1790,12 @@ public class SDLGPURenderBackend extends RenderBackend {
     @Override public void samplerParameteri(int sampler, int pname, int param) {
         if (sampler == 0) return;
         final TextureSamplerState ss = resourceManager.getOrCreateSamplerObject(sampler);
-        switch (pname) {
-            case GL11.GL_TEXTURE_MIN_FILTER -> ss.minFilter = param;
-            case GL11.GL_TEXTURE_MAG_FILTER -> ss.magFilter = param;
-            case GL11.GL_TEXTURE_WRAP_S -> ss.wrapS = param;
-            case GL11.GL_TEXTURE_WRAP_T -> ss.wrapT = param;
-            case GL12.GL_TEXTURE_WRAP_R -> ss.wrapR = param;
-            case GL12.GL_TEXTURE_MIN_LOD -> ss.minLod = (float) param;
-            case GL12.GL_TEXTURE_MAX_LOD -> ss.maxLod = (float) param;
-            case GL14.GL_TEXTURE_COMPARE_MODE -> ss.compareMode = param;
-            case GL14.GL_TEXTURE_COMPARE_FUNC -> ss.compareFunc = param;
-            case EXTTextureFilterAnisotropic.GL_TEXTURE_MAX_ANISOTROPY_EXT -> ss.maxAnisotropy = param;
-            default -> { return; }
-        }
-        ss.sdlSampler = 0;
-        s().samplerBindGen++;
+        if (ss.invalidate(ss.seti(pname, param))) s().samplerBindGen++;
     }
     @Override public void samplerParameterf(int sampler, int pname, float param) {
         if (sampler == 0) return;
         final TextureSamplerState ss = resourceManager.getOrCreateSamplerObject(sampler);
-        switch (pname) {
-            case GL12.GL_TEXTURE_MIN_LOD -> ss.minLod = param;
-            case GL12.GL_TEXTURE_MAX_LOD -> ss.maxLod = param;
-            case GL14.GL_TEXTURE_LOD_BIAS -> ss.lodBias = param;
-            case EXTTextureFilterAnisotropic.GL_TEXTURE_MAX_ANISOTROPY_EXT -> ss.maxAnisotropy = param;
-            default -> { samplerParameteri(sampler, pname, (int) param); return; }
-        }
-        ss.sdlSampler = 0;
-        s().samplerBindGen++;
+        if (ss.invalidate(ss.setf(pname, param))) s().samplerBindGen++;
     }
 
     @Override public int genFramebuffers() {
diff --git a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/device/Device.java b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/device/Device.java
index ddb25cd78..dd87d8967 100644
--- a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/device/Device.java
+++ b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/device/Device.java
@@ -44,6 +44,9 @@ public final class Device {
     private boolean claimed;
     private int supportedShaderFormats;
     private String driverName;
+    private boolean fencePollEnabled;
+    private boolean fenceQueryInverted;
+    private final FenceReleaser fenceReleaser = new FenceReleaser(fence -> device == 0 || FenceWait.isSignaled(this, fence), fence -> { if (device != 0) SDL_ReleaseGPUFence(device, fence); });
     private String deviceName;
     private String driverVersion;
     private String driverInfo;
@@ -84,8 +87,12 @@ public final class Device {
         return userHint.isEmpty() && windows ? "vulkan" : null;
     }
 
+    static boolean isMetal(String driverName) {
+        return "metal".equalsIgnoreCase(driverName);
+    }
+
     static boolean metalNeedsNewerSdl(String driverName, int sdlVersion) {
-        return "metal".equalsIgnoreCase(driverName) && sdlVersion < SDLVersion.SDL_VERSIONNUM(3, 4, 6);
+        return isMetal(driverName) && sdlVersion < SDLVersion.SDL_VERSIONNUM(3, 4, 6);
     }
 
     public boolean createDevice() {
@@ -129,9 +136,21 @@ public final class Device {
             return false;
         }
 
+        probeFences(ver);
+
         return true;
     }
 
+    private void probeFences(int ver) {
+        fencePollEnabled = FenceWait.pollEnabled(driverName, ver);
+        final boolean expectInverted = isMetal(driverName) && ver == SDLVersion.SDL_VERSIONNUM(3, 4, 14);
+        fenceQueryInverted = FenceProbe.queryInverted(device, driverName, expectInverted);
+        LOG.info("SDL {}.{}.{} driver={} fenceQueryInverted={} fencePoll={}", SDLVersion.SDL_VERSIONNUM_MAJOR(ver), SDLVersion.SDL_VERSIONNUM_MINOR(ver), SDLVersion.SDL_VERSIONNUM_MICRO(ver), driverName, fenceQueryInverted, fencePollEnabled);
+        if (fenceQueryInverted != expectInverted) {
+            LOG.warn("Fence query probe disagrees with the SDL version table: inverted={}, expected {}", fenceQueryInverted, expectInverted);
+        }
+    }
+
     private long createGPUDevice(boolean gpuDebug, String forcedDriver) {
         long dev = SDL_CreateGPUDevice(REQUESTED_SHADER_FORMATS, gpuDebug, forcedDriver);
         if (dev == 0 && forcedDriver != null) {
@@ -204,9 +223,12 @@ public final class Device {
             if (window != 0) SDL_ReleaseWindowFromGPUDevice(device, window);
             claimed = false;
         }
+        fenceReleaser.releaseAll();
         SDL_DestroyGPUDevice(device);
         device = 0;
         driverName = null;
+        fencePollEnabled = false;
+        fenceQueryInverted = false;
         deviceName = null;
         driverVersion = null;
         driverInfo = null;
@@ -268,6 +290,18 @@ public final class Device {
         return driverName;
     }
 
+    public boolean isFencePollEnabled() {
+        return fencePollEnabled;
+    }
+
+    public boolean isFenceQueryInverted() {
+        return fenceQueryInverted;
+    }
+
+    public FenceReleaser fenceReleaser() {
+        return fenceReleaser;
+    }
+
     public Thread getWindowThread() {
         return windowThread;
     }
diff --git a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/device/FenceProbe.java b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/device/FenceProbe.java
new file mode 100644
index 000000000..2a1170af6
--- /dev/null
+++ b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/device/FenceProbe.java
@@ -0,0 +1,43 @@
+package com.gtnewhorizons.angelica.sdlgpu.device;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.lwjgl.sdl.SDLError;
+import org.lwjgl.system.MemoryStack;
+
+import static org.lwjgl.sdl.SDLGPU.SDL_AcquireGPUCommandBuffer;
+import static org.lwjgl.sdl.SDLGPU.SDL_QueryGPUFence;
+import static org.lwjgl.sdl.SDLGPU.SDL_ReleaseGPUFence;
+import static org.lwjgl.sdl.SDLGPU.SDL_WaitForGPUFences;
+
+final class FenceProbe {
+    private static final Logger LOG = LogManager.getLogger("Angelica-SDLGPU");
+
+    private FenceProbe() {}
+
+    static boolean queryInverted(long dev, String driverName, boolean onFailure) {
+        final long cb = SDL_AcquireGPUCommandBuffer(dev);
+        if (cb == 0) {
+            LOG.warn("Fence probe: SDL_AcquireGPUCommandBuffer failed: {}; using the SDL version table ({})", SDLError.SDL_GetError(), onFailure);
+            return onFailure;
+        }
+        final long fence = Submits.submitAndAcquireFence(cb);
+        if (fence == 0) {
+            LOG.warn("Fence probe: submit and acquire fence failed: {}; using the SDL version table ({})", SDLError.SDL_GetError(), onFailure);
+            return onFailure;
+        }
+        final boolean waitOk;
+        final boolean rawSignaled;
+        try (MemoryStack stack = MemoryStack.stackPush()) {
+            waitOk = SDL_WaitForGPUFences(dev, true, stack.pointers(fence));
+            rawSignaled = SDL_QueryGPUFence(dev, fence);
+        } finally {
+            SDL_ReleaseGPUFence(dev, fence);
+        }
+        final boolean metal = Device.isMetal(driverName);
+        if (waitOk && !rawSignaled && !metal) {
+            LOG.error("SDL_QueryGPUFence reports a waited fence as busy on driver {}; not inverting the query outside Metal", driverName);
+        }
+        return metal && waitOk && !rawSignaled;
+    }
+}
diff --git a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/device/FenceReleaser.java b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/device/FenceReleaser.java
new file mode 100644
index 000000000..a0beec0bc
--- /dev/null
+++ b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/device/FenceReleaser.java
@@ -0,0 +1,43 @@
+package com.gtnewhorizons.angelica.sdlgpu.device;
+
+import it.unimi.dsi.fastutil.longs.LongArrayList;
+
+import java.util.function.LongConsumer;
+import java.util.function.LongPredicate;
+
+public final class FenceReleaser {
+    private final LongPredicate signaled;
+    private final LongConsumer releaser;
+    private final LongArrayList pending = new LongArrayList();
+
+    FenceReleaser(LongPredicate signaled, LongConsumer releaser) {
+        this.signaled = signaled;
+        this.releaser = releaser;
+    }
+
+    public synchronized void release(long fence) {
+        if (fence == 0) return;
+        if (signaled.test(fence)) {
+            releaser.accept(fence);
+        } else {
+            pending.add(fence);
+        }
+    }
+
+    public synchronized void drain() {
+        for (int i = pending.size() - 1; i >= 0; i--) {
+            final long fence = pending.getLong(i);
+            if (!signaled.test(fence)) continue;
+            releaser.accept(fence);
+            final long last = pending.popLong();
+            if (i < pending.size()) pending.set(i, last);
+        }
+    }
+
+    public synchronized void releaseAll() {
+        for (int i = 0; i < pending.size(); i++) {
+            releaser.accept(pending.getLong(i));
+        }
+        pending.clear();
+    }
+}
diff --git a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/device/FenceWait.java b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/device/FenceWait.java
new file mode 100644
index 000000000..c95ec3733
--- /dev/null
+++ b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/device/FenceWait.java
@@ -0,0 +1,94 @@
+package com.gtnewhorizons.angelica.sdlgpu.device;
+
+import com.gtnewhorizons.angelica.glsm.profiling.DebugCounters;
+import org.lwjgl.system.MemoryStack;
+
+import java.util.concurrent.locks.LockSupport;
+
+import static org.lwjgl.sdl.SDLGPU.SDL_QueryGPUFence;
+import static org.lwjgl.sdl.SDLGPU.SDL_WaitForGPUFences;
+import static org.lwjgl.sdl.SDLVersion.SDL_VERSIONNUM;
+
+// SDL < 3.4.14 METAL_WaitForFences busy-spins on the completion flag; poll + park there instead.
+public final class FenceWait {
+    public static final long FOREVER = Long.MAX_VALUE;
+
+    static final long SPIN_NS = 20_000L;
+    static final long PARK_MAX_NS = 50_000L;
+
+    interface Ops {
+        boolean query(long dev, long fence);
+        void waitNative(long dev, long fence);
+        long nanoTime();
+        void park(long nanos);
+    }
+
+    private static final class NativeOps implements Ops {
+        private final boolean inverted;
+
+        NativeOps(boolean inverted) { this.inverted = inverted; }
+
+        @Override public boolean query(long dev, long fence) { return SDL_QueryGPUFence(dev, fence) != inverted; }
+
+        @Override public void waitNative(long dev, long fence) {
+            try (MemoryStack stack = MemoryStack.stackPush()) {
+                SDL_WaitForGPUFences(dev, true, stack.pointers(fence));
+            }
+        }
+
+        @Override public long nanoTime() { return System.nanoTime(); }
+        @Override public void park(long nanos) { LockSupport.parkNanos(nanos); }
+    }
+
+    private static final Ops NATIVE = new NativeOps(false);
+    private static final Ops NATIVE_INVERTED = new NativeOps(true);
+
+    private FenceWait() {}
+
+    private static Ops ops(Device device) {
+        return device.isFenceQueryInverted() ? NATIVE_INVERTED : NATIVE;
+    }
+
+    public static boolean isSignaled(Device device, long fence) {
+        return ops(device).query(device.getDevice(), fence);
+    }
+
+    public static boolean await(Device device, long fence, long timeoutNs) {
+        final long start = System.nanoTime();
+        final boolean signaled = await(device.getDevice(), fence, timeoutNs, device.isFencePollEnabled(), ops(device));
+        DebugCounters.FENCE_WAIT_NANOS.add(System.nanoTime() - start);
+        return signaled;
+    }
+
+    static boolean pollEnabled(String driverName, int sdlVersion) {
+        return Device.isMetal(driverName) && sdlVersion < SDL_VERSIONNUM(3, 4, 14);
+    }
+
+    // timeoutNs < 0 is GL_TIMEOUT_IGNORED read as signed; treated as forever
+    static boolean await(long dev, long fence, long timeoutNs, boolean pollForever, Ops ops) {
+        if (ops.query(dev, fence)) return true;
+        if (timeoutNs == 0) return false;
+        final boolean forever = timeoutNs < 0 || timeoutNs == FOREVER;
+        if (forever && !pollForever) {
+            ops.waitNative(dev, fence);
+            return true;
+        }
+        boolean interrupted = false;
+        try {
+            final long start = ops.nanoTime();
+            while (true) {
+                final long elapsed = ops.nanoTime() - start;
+                if (ops.query(dev, fence)) return true;
+                if (!forever && elapsed >= timeoutNs) return false;
+                if (elapsed < SPIN_NS) {
+                    Thread.onSpinWait();
+                    continue;
+                }
+                if (Thread.interrupted()) interrupted = true;
+                ops.park(forever ? PARK_MAX_NS : Math.min(PARK_MAX_NS, timeoutNs - elapsed));
+            }
+        } finally {
+            if (interrupted) Thread.currentThread().interrupt();
+        }
+    }
+}
diff --git a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/device/Submits.java b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/device/Submits.java
new file mode 100644
index 000000000..4be1e1720
--- /dev/null
+++ b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/device/Submits.java
@@ -0,0 +1,22 @@
+package com.gtnewhorizons.angelica.sdlgpu.device;
+
+import static org.lwjgl.sdl.SDLGPU.SDL_SubmitGPUCommandBuffer;
+import static org.lwjgl.sdl.SDLGPU.SDL_SubmitGPUCommandBufferAndAcquireFence;
+
+public final class Submits {
+    private static final Object LOCK = new Object();
+
+    private Submits() {}
+
+    public static boolean submit(long commandBuffer) {
+        synchronized (LOCK) {
+            return SDL_SubmitGPUCommandBuffer(commandBuffer);
+        }
+    }
+
+    public static long submitAndAcquireFence(long commandBuffer) {
+        synchronized (LOCK) {
+            return SDL_SubmitGPUCommandBufferAndAcquireFence(commandBuffer);
+        }
+    }
+}
diff --git a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/frame/FenceTracker.java b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/frame/FenceTracker.java
index c9e42ee04..df134b033 100644
--- a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/frame/FenceTracker.java
+++ b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/frame/FenceTracker.java
@@ -2,17 +2,14 @@ package com.gtnewhorizons.angelica.sdlgpu.frame;
 
 import com.gtnewhorizons.angelica.glsm.profiling.Tracy;
 import com.gtnewhorizons.angelica.sdlgpu.device.Device;
+import com.gtnewhorizons.angelica.sdlgpu.device.FenceWait;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import com.gtnewhorizons.angelica.sdlgpu.frame.FrameManager;
 import it.unimi.dsi.fastutil.longs.Long2IntOpenHashMap;
 import it.unimi.dsi.fastutil.longs.Long2LongOpenHashMap;
 import it.unimi.dsi.fastutil.longs.LongArrayList;
-import org.lwjgl.PointerBuffer;
 import org.lwjgl.opengl.GL32;
-import org.lwjgl.system.MemoryStack;
-
-import static org.lwjgl.sdl.SDLGPU.*;
 
 public final class FenceTracker {
     private static final Logger LOG = LogManager.getLogger("Angelica-SDLGPU");
@@ -87,16 +84,16 @@ public final class FenceTracker {
             fence = flushForUnresolved(sync);
             if (fence == 0) return GL32.GL_TIMEOUT_EXPIRED;
         }
-        if (SDL_QueryGPUFence(device.getDevice(), fence)) return GL32.GL_ALREADY_SIGNALED;
+        if (FenceWait.isSignaled(device, fence)) return GL32.GL_ALREADY_SIGNALED;
         if (timeout == 0) return GL32.GL_TIMEOUT_EXPIRED;
+        final boolean signaled;
         Tracy.beginZone(Z_SDL_FENCE_WAIT);
-        try (var stack = MemoryStack.stackPush()) {
-            final PointerBuffer fences = stack.mallocPointer(1).put(0, fence);
-            SDL_WaitForGPUFences(device.getDevice(), true, fences);
+        try {
+            signaled = FenceWait.await(device, fence, timeout);
         } finally {
             Tracy.endZone();
         }
-        return GL32.GL_CONDITION_SATISFIED;
+        return signaled ? GL32.GL_CONDITION_SATISFIED : GL32.GL_TIMEOUT_EXPIRED;
     }
 
     public void deleteSync(long sync) {
@@ -105,15 +102,14 @@ public final class FenceTracker {
         final int newCount = fenceRefcounts.addTo(fence, -1) - 1;
         if (newCount <= 0) {
             fenceRefcounts.remove(fence);
-            SDL_ReleaseGPUFence(device.getDevice(), fence);
+            device.fenceReleaser().release(fence);
         }
     }
 
     public void dispose() {
-        final long dev = device.getDevice();
-        if (dev != 0) {
+        if (device.getDevice() != 0) {
             for (long fence : fenceRefcounts.keySet()) {
-                SDL_ReleaseGPUFence(dev, fence);
+                device.fenceReleaser().release(fence);
             }
         }
         fenceRefcounts.clear();
@@ -125,7 +121,7 @@ public final class FenceTracker {
         if (!fenceMap.containsKey(sync)) return true;
         final long fence = fenceMap.get(sync);
         if (fence == 0) return false;
-        return SDL_QueryGPUFence(device.getDevice(), fence);
+        return FenceWait.isSignaled(device, fence);
     }
 
     public int getSyncStatus(long sync) {
@@ -139,11 +135,9 @@ public final class FenceTracker {
             flushForUnresolved(sync);
             return;
         }
-        if (SDL_QueryGPUFence(device.getDevice(), fence)) return;
         Tracy.beginZone(Z_SDL_FENCE_WAIT);
-        try (var stack = MemoryStack.stackPush()) {
-            final PointerBuffer fences = stack.mallocPointer(1).put(0, fence);
-            SDL_WaitForGPUFences(device.getDevice(), true, fences);
+        try {
+            FenceWait.await(device, fence, FenceWait.FOREVER);
         } finally {
             Tracy.endZone();
         }
diff --git a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/frame/FrameManager.java b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/frame/FrameManager.java
index 906be6b5f..7ecef04fd 100644
--- a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/frame/FrameManager.java
+++ b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/frame/FrameManager.java
@@ -2,8 +2,11 @@ package com.gtnewhorizons.angelica.sdlgpu.frame;
 
 import com.gtnewhorizons.angelica.config.SystemProperties;
 import com.gtnewhorizons.angelica.glsm.backend.BackendManager;
+import com.gtnewhorizons.angelica.glsm.backend.VSyncMode;
+import com.gtnewhorizons.angelica.glsm.profiling.DebugCounters;
 import com.gtnewhorizons.angelica.glsm.profiling.Tracy;
 import com.gtnewhorizons.angelica.sdlgpu.device.Device;
+import com.gtnewhorizons.angelica.sdlgpu.device.Submits;
 import com.gtnewhorizons.angelica.sdlgpu.resource.FboState;
 import com.gtnewhorizons.angelica.sdlgpu.resource.ResourceManager;
 import com.gtnewhorizons.angelica.sdlgpu.util.MemoryAccess;
@@ -584,14 +587,7 @@ public final class FrameManager {
         if (f.commandBuffer != 0) {
             Tracy.beginZone(Z_SDL_SUBMIT);
             try {
-                if (f.wantFenceOnNextSubmit) {
-                    f.wantFenceOnNextSubmit = false;
-                    if (f.lastAcquiredFence != 0) SDL_ReleaseGPUFence(device.getDevice(), f.lastAcquiredFence);
-                    f.lastAcquiredFence = SDL_SubmitGPUCommandBufferAndAcquireFence(f.commandBuffer);
-                    if (f.lastAcquiredFence == 0) {
-                        device.reportGpuFailure("submit+acquireFence GPU command buffer");
-                    }
-                } else if (!SDL_SubmitGPUCommandBuffer(f.commandBuffer)) {
+                if (!submitTracked(f, f.commandBuffer)) {
                     device.reportGpuFailure("submit GPU command buffer");
                 }
             } finally {
@@ -658,14 +654,7 @@ public final class FrameManager {
         endRenderPassIfActive(f, PASS_END_FRAME_END);
         Tracy.beginZone(Z_SDL_SUBMIT);
         try {
-            if (f.wantFenceOnNextSubmit) {
-                f.wantFenceOnNextSubmit = false;
-                if (f.lastAcquiredFence != 0) SDL_ReleaseGPUFence(device.getDevice(), f.lastAcquiredFence);
-                f.lastAcquiredFence = SDL_SubmitGPUCommandBufferAndAcquireFence(f.commandBuffer);
-                if (f.lastAcquiredFence == 0) {
-                    device.reportGpuFailure("mid-frame submit+acquireFence");
-                }
-            } else if (!SDL_SubmitGPUCommandBuffer(f.commandBuffer)) {
+            if (!submitTracked(f, f.commandBuffer)) {
                 device.reportGpuFailure("mid-frame submit");
             }
         } finally {
@@ -737,6 +726,14 @@ public final class FrameManager {
         flushPendingUploadCommandBuffer(frame());
     }
 
+    private boolean submitTracked(FrameState f, long cb) {
+        if (!f.wantFenceOnNextSubmit) return Submits.submit(cb);
+        f.wantFenceOnNextSubmit = false;
+        if (f.lastAcquiredFence != 0) device.fenceReleaser().release(f.lastAcquiredFence);
+        f.lastAcquiredFence = Submits.submitAndAcquireFence(cb);
+        return f.lastAcquiredFence != 0;
+    }
+
     private void flushPendingUploadCommandBuffer(FrameState f) {
         final boolean sync = f.syncOnNextFlush;
         if (f.pendingUploadCommandBuffer == 0) {
@@ -753,14 +750,7 @@ public final class FrameManager {
             Tracy.beginZone(Z_SDL_SUBMIT);
             final boolean submitted;
             try {
-                if (f.wantFenceOnNextSubmit) {
-                    f.wantFenceOnNextSubmit = false;
-                    if (f.lastAcquiredFence != 0) SDL_ReleaseGPUFence(device.getDevice(), f.lastAcquiredFence);
-                    f.lastAcquiredFence = SDL_SubmitGPUCommandBufferAndAcquireFence(f.pendingUploadCommandBuffer);
-                    submitted = f.lastAcquiredFence != 0;
-                } else {
-                    submitted = SDL_SubmitGPUCommandBuffer(f.pendingUploadCommandBuffer);
-                }
+                submitted = submitTracked(f, f.pendingUploadCommandBuffer);
             } finally {
                 Tracy.endZone();
             }
@@ -907,7 +897,7 @@ public final class FrameManager {
         f.uboPushViewSource.clear();
 
         if (f.lastAcquiredFence != 0) {
-            SDL_ReleaseGPUFence(device.getDevice(), f.lastAcquiredFence);
+            device.fenceReleaser().release(f.lastAcquiredFence);
             f.lastAcquiredFence = 0;
         }
     }
@@ -947,7 +937,11 @@ public final class FrameManager {
         final Presenter p = presenter;
         if (p != null) {
             f.presentedThisFrame = true;
-            p.requestPresent(srcTexture, srcW, srcH, flipMode);
+            if (!splash && BackendManager.RENDER_BACKEND.getEffectiveVSyncMode() == VSyncMode.OFF) {
+                if (!p.tryRequestPresent(srcTexture, srcW, srcH, flipMode)) notePresentSkip(f);
+            } else {
+                p.requestPresent(srcTexture, srcW, srcH, flipMode);
+            }
         } else {
             presentBlit(f, srcTexture, srcW, srcH, flipMode);
         }
@@ -1027,7 +1021,7 @@ public final class FrameManager {
             final IntBuffer pHeight = stack.ints(0);
             Tracy.beginZone(Z_SDL_ACQUIRE_WAIT);
             try {
-                callOk = SDL_AcquireGPUSwapchainTexture(cb, window, pTexture, pWidth, pHeight);
+                callOk = device.isFenceQueryInverted() ? SDL_WaitAndAcquireGPUSwapchainTexture(cb, window, pTexture, pWidth, pHeight) : SDL_AcquireGPUSwapchainTexture(cb, window, pTexture, pWidth, pHeight);
             } finally {
                 Tracy.endZone();
             }
@@ -1042,6 +1036,7 @@ public final class FrameManager {
         final long tEnd = System.nanoTime();
 
         if (!callOk || tex == 0) {
+            if (callOk) DebugCounters.EMPTY_ACQUIRES.increment();
             SDL_CancelGPUCommandBuffer(cb);
             f.swapchainUnavailable = true;
             notePresentSkip(f);
@@ -1060,10 +1055,11 @@ public final class FrameManager {
             nSDL_BlitGPUTexture(cb, info);
         }
 
-        if (!SDL_SubmitGPUCommandBuffer(cb)) {
+        if (!Submits.submit(cb)) {
             device.reportGpuFailure("submit present blit");
             return false;
         }
+        DebugCounters.PRESENTS.increment();
         f.presentedThisFrame = true;
         if (afterPresent != null) afterPresent.run();
         return true;
diff --git a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/frame/Presenter.java b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/frame/Presenter.java
index 054b2eb7c..c5e90e8a0 100644
--- a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/frame/Presenter.java
+++ b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/frame/Presenter.java
@@ -1,5 +1,7 @@
 package com.gtnewhorizons.angelica.sdlgpu.frame;
 
+import com.gtnewhorizons.angelica.glsm.backend.MainThreadPump;
+
 import java.util.concurrent.Executor;
 import java.util.concurrent.Semaphore;
 
@@ -7,6 +9,7 @@ public final class Presenter {
 
     private final FrameManager frameManager;
     private final Executor windowThreadExecutor;
+    private final MainThreadPump pump;
     private final Semaphore pending = new Semaphore(1);
     private final Runnable task;
 
@@ -15,13 +18,16 @@ public final class Presenter {
     private int srcH;
     private int flipMode;
 
-    public Presenter(FrameManager frameManager, Executor windowThreadExecutor) {
+    public Presenter(FrameManager frameManager, Executor windowThreadExecutor, MainThreadPump pump) {
         this.frameManager = frameManager;
         this.windowThreadExecutor = windowThreadExecutor;
+        this.pump = pump;
         this.task = () -> {
             try {
+                pump.runPresentPump();
                 frameManager.presentOnWindowThread(srcTexture, srcW, srcH, flipMode);
             } finally {
+                pump.endPresent();
                 pending.release();
             }
         };
@@ -29,16 +35,30 @@ public final class Presenter {
 
     public void requestPresent(long srcTexture, int srcW, int srcH, int flipMode) {
         pending.acquireUninterruptibly();
+        submit(srcTexture, srcW, srcH, flipMode);
+    }
+
+    public boolean tryRequestPresent(long srcTexture, int srcW, int srcH, int flipMode) {
+        if (!pending.tryAcquire()) return false;
+        submit(srcTexture, srcW, srcH, flipMode);
+        return true;
+    }
+
+    private void submit(long srcTexture, int srcW, int srcH, int flipMode) {
         this.srcTexture = srcTexture;
         this.srcW = srcW;
         this.srcH = srcH;
         this.flipMode = flipMode;
+        pump.beginPresent();
         boolean submitted = false;
         try {
             windowThreadExecutor.execute(task);
             submitted = true;
         } finally {
-            if (!submitted) pending.release();
+            if (!submitted) {
+                pump.endPresent();
+                pending.release();
+            }
         }
     }
 
diff --git a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/PersistentBufferSync.java b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/PersistentBufferSync.java
index 9df5ce985..2a0188b80 100644
--- a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/PersistentBufferSync.java
+++ b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/PersistentBufferSync.java
@@ -41,11 +41,11 @@ public final class PersistentBufferSync {
     }
 
     public void uploadDirtyPersistentRegion()   { processDirtyPersistentRegions(false); }
-    public void enqueueDirtyPersistentRegions() { processDirtyPersistentRegions(true); }
+    public int enqueueDirtyPersistentRegions()  { return processDirtyPersistentRegions(true); }
 
-    private void processDirtyPersistentRegions(boolean defer) {
-        if (!resourceManager.hasDirtyPersistentRegions()) return;
-        if (!defer && frameManager.getCommandBuffer() == 0) return;
+    private int processDirtyPersistentRegions(boolean defer) {
+        if (!resourceManager.hasDirtyPersistentRegions()) return 0;
+        if (!defer && frameManager.getCommandBuffer() == 0) return 0;
         final Snapshot snap = snapshotTL.get();
         final IntArrayList keys = snap.keys;
         final ArrayList<PersistentMapping> vals = snap.vals;
@@ -55,6 +55,7 @@ public final class PersistentBufferSync {
             snap.version = version;
         }
         final int n = keys.size();
+        int enqueued = 0;
         for (int i = 0; i < n; i++) {
             final PersistentMapping pm = vals.get(i);
             if (!pm.isDirty()) continue;
@@ -69,6 +70,7 @@ public final class PersistentBufferSync {
                 final long seq = sink.nextSeq();
                 pm.lastEnqueuedSeq = seq;
                 sink.enqueue(TransferThread.StagingReadUpload.acquire(pm.staging, off, size, gpuHandle, off, seq, false));
+                enqueued++;
             } else {
                 pm.staging.position((int) off).limit((int) (off + size));
                 resourceManager.uploadToBuffer(frameManager.ensureCopyPass(), pm.staging, gpuHandle, off, false);
@@ -76,6 +78,7 @@ public final class PersistentBufferSync {
             }
             resourceManager.clearPersistentDirty();
         }
+        return enqueued;
     }
 
     public static void mirrorPersistentCopy(ByteBuffer srcStaging, long srcOffset, ByteBuffer dstStaging, long dstOffset, long size) {
diff --git a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/ResourceManager.java b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/ResourceManager.java
index bad446614..1466de118 100644
--- a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/ResourceManager.java
+++ b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/ResourceManager.java
@@ -4,7 +4,7 @@ import java.util.function.LongConsumer;
 import com.gtnewhorizons.angelica.sdlgpu.pipeline.Hashing;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
-import org.lwjgl.PointerBuffer;
+import com.gtnewhorizons.angelica.sdlgpu.device.FenceWait;
 import org.lwjgl.opengl.GL11;
 import org.lwjgl.opengl.GL12;
 import org.lwjgl.opengl.GL13;
@@ -47,6 +47,7 @@ import static org.lwjgl.system.MemoryUtil.memFree;
 import com.gtnewhorizons.angelica.glsm.profiling.Tracy;
 import com.gtnewhorizons.angelica.glsm.texture.TextureStaging;
 import com.gtnewhorizons.angelica.sdlgpu.device.Device;
+import com.gtnewhorizons.angelica.sdlgpu.device.Submits;
 import com.gtnewhorizons.angelica.sdlgpu.frame.ContextState;
 import com.gtnewhorizons.angelica.sdlgpu.frame.FrameManager;
 import com.gtnewhorizons.angelica.sdlgpu.pipeline.EBOSplitScanner;
@@ -1561,7 +1562,7 @@ public final class ResourceManager {
         f.arenaCopyPass = SDL_BeginGPUCopyPass(f.arenaCommandBuffer);
         if (f.arenaCopyPass == 0) {
             LOG.error("Failed to begin arena copy pass: {}", SDLError.SDL_GetError());
-            SDL_SubmitGPUCommandBuffer(f.arenaCommandBuffer);
+            Submits.submit(f.arenaCommandBuffer);
             f.arenaCommandBuffer = 0;
             unmapArena(f);
             return false;
@@ -1589,7 +1590,7 @@ public final class ResourceManager {
             f.arenaCopyPass = 0;
         }
         if (f.arenaCommandBuffer != 0) {
-            if (!SDL_SubmitGPUCommandBuffer(f.arenaCommandBuffer)) {
+            if (!Submits.submit(f.arenaCommandBuffer)) {
                 device.reportGpuFailure("submit arena upload command buffer");
             }
             f.arenaCommandBuffer = 0;
@@ -1884,17 +1885,16 @@ public final class ResourceManager {
             SDL_DownloadFromGPUTexture(copyPass, src, dst);
             SDL_EndGPUCopyPass(copyPass);
 
-            final long fence = SDL_SubmitGPUCommandBufferAndAcquireFence(commandBuffer);
+            final long fence = Submits.submitAndAcquireFence(commandBuffer);
             if (fence == 0) {
                 LOG.error("Failed to submit download command buffer: {}", SDLError.SDL_GetError());
                 SDL_ReleaseGPUTransferBuffer(device.getDevice(), xfer);
                 return;
             }
             try {
-                final PointerBuffer fences = stack.pointers(fence);
-                SDL_WaitForGPUFences(device.getDevice(), true, fences);
+                FenceWait.await(device, fence, FenceWait.FOREVER);
             } finally {
-                SDL_ReleaseGPUFence(device.getDevice(), fence);
+                device.fenceReleaser().release(fence);
             }
 
             final long mappedPtr = nSDL_MapGPUTransferBuffer(device.getDevice(), xfer, false);
@@ -1937,17 +1937,16 @@ public final class ResourceManager {
             SDL_DownloadFromGPUBuffer(copyPass, src, dst);
             SDL_EndGPUCopyPass(copyPass);
 
-            final long fence = SDL_SubmitGPUCommandBufferAndAcquireFence(commandBuffer);
+            final long fence = Submits.submitAndAcquireFence(commandBuffer);
             if (fence == 0) {
                 LOG.error("Failed to submit buffer download command buffer: {}", SDLError.SDL_GetError());
                 SDL_ReleaseGPUTransferBuffer(device.getDevice(), xfer);
                 return;
             }
             try {
-                final PointerBuffer fences = stack.pointers(fence);
-                SDL_WaitForGPUFences(device.getDevice(), true, fences);
+                FenceWait.await(device, fence, FenceWait.FOREVER);
             } finally {
-                SDL_ReleaseGPUFence(device.getDevice(), fence);
+                device.fenceReleaser().release(fence);
             }
 
             final long mappedPtr = nSDL_MapGPUTransferBuffer(device.getDevice(), xfer, false);
@@ -2124,7 +2123,7 @@ public final class ResourceManager {
                 SDL_UploadToGPUTexture(copyPass, src, dst, false);
                 SDL_EndGPUCopyPass(copyPass);
             }
-            SDL_SubmitGPUCommandBuffer(cb);
+            Submits.submit(cb);
         }
         releaseTransferBuffer(xfer);
     }
@@ -2151,7 +2150,7 @@ public final class ResourceManager {
                 SDL_UploadToGPUBuffer(copyPass, src, dst, false);
                 SDL_EndGPUCopyPass(copyPass);
             }
-            SDL_SubmitGPUCommandBuffer(cb);
+            Submits.submit(cb);
         }
         releaseTransferBuffer(xfer);
     }
@@ -2264,7 +2263,7 @@ public final class ResourceManager {
                     final var dst = SDL_GPUBufferRegion.calloc(stack).buffer(dummyVertexBuffer).offset(0).size(DUMMY_VBO_SIZE);
                     SDL_UploadToGPUBuffer(copyPass, src, dst, false);
                     SDL_EndGPUCopyPass(copyPass);
-                    SDL_SubmitGPUCommandBuffer(cb);
+                    Submits.submit(cb);
                 }
                 releaseTransferBufferHandle(xfer);
             }
diff --git a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/TextureOps.java b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/TextureOps.java
index 63af862a2..c51afca9e 100644
--- a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/TextureOps.java
+++ b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/TextureOps.java
@@ -1,15 +1,13 @@
 package com.gtnewhorizons.angelica.sdlgpu.resource;
 
 import com.gtnewhorizons.angelica.sdlgpu.device.Device;
+import com.gtnewhorizons.angelica.sdlgpu.device.Submits;
 import com.gtnewhorizons.angelica.sdlgpu.frame.ContextState;
 import com.gtnewhorizons.angelica.sdlgpu.frame.FrameManager;
 import com.gtnewhorizons.angelica.sdlgpu.resource.ResourceManager;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
-import org.lwjgl.opengl.EXTTextureFilterAnisotropic;
 import org.lwjgl.opengl.GL11;
-import org.lwjgl.opengl.GL12;
-import org.lwjgl.opengl.GL14;
 import org.lwjgl.sdl.SDLError;
 import org.lwjgl.sdl.SDL_GPUBlitInfo;
 import org.lwjgl.sdl.SDL_GPUTextureLocation;
@@ -70,38 +68,13 @@ public final class TextureOps {
     public void texParameteri(ContextState st, int pname, int param, int glId) {
         if (glId == 0) return;
         final TextureSamplerState ss = resourceManager.getOrCreateTexSamplerState(glId);
-        switch (pname) {
-            case GL11.GL_TEXTURE_MIN_FILTER -> ss.minFilter = param;
-            case GL11.GL_TEXTURE_MAG_FILTER -> ss.magFilter = param;
-            case GL11.GL_TEXTURE_WRAP_S -> ss.wrapS = param;
-            case GL11.GL_TEXTURE_WRAP_T -> ss.wrapT = param;
-            case GL12.GL_TEXTURE_WRAP_R -> ss.wrapR = param;
-            case GL12.GL_TEXTURE_MAX_LEVEL -> {
-                ss.maxLevel = param; return;
-            }
-            case GL12.GL_TEXTURE_MIN_LOD -> ss.minLod = (float) param;
-            case GL12.GL_TEXTURE_MAX_LOD -> ss.maxLod = (float) param;
-            case GL14.GL_TEXTURE_COMPARE_MODE -> ss.compareMode = param;
-            case GL14.GL_TEXTURE_COMPARE_FUNC -> ss.compareFunc = param;
-            case EXTTextureFilterAnisotropic.GL_TEXTURE_MAX_ANISOTROPY_EXT -> ss.maxAnisotropy = param;
-            default -> { return; }
-        }
-        ss.sdlSampler = 0;
-        st.samplerBindGen++;
+        if (ss.invalidate(ss.seti(pname, param))) st.samplerBindGen++;
     }
 
     public void texParameterf(ContextState st, int pname, float param, int glId) {
         if (glId == 0) return;
         final TextureSamplerState ss = resourceManager.getOrCreateTexSamplerState(glId);
-        switch (pname) {
-            case GL12.GL_TEXTURE_MIN_LOD -> ss.minLod = param;
-            case GL12.GL_TEXTURE_MAX_LOD -> ss.maxLod = param;
-            case GL14.GL_TEXTURE_LOD_BIAS -> ss.lodBias = param;
-            case EXTTextureFilterAnisotropic.GL_TEXTURE_MAX_ANISOTROPY_EXT -> ss.maxAnisotropy = param;
-            default -> { texParameteri(st, pname, (int) param, glId); return; }
-        }
-        ss.sdlSampler = 0;
-        st.samplerBindGen++;
+        if (ss.invalidate(ss.setf(pname, param))) st.samplerBindGen++;
     }
 
     /// requires a flush + submit to not read stale data
@@ -291,7 +264,7 @@ public final class TextureOps {
             SDL_GenerateMipmapsForGPUTexture(uploadCb, handle);
         }
 
-        if (!SDL_SubmitGPUCommandBuffer(uploadCb)) {
+        if (!Submits.submit(uploadCb)) {
             device.reportGpuFailure("submit mipmap generation CB");
         }
         frameManager.noteMipGenSubmit();
diff --git a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/TextureSamplerState.java b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/TextureSamplerState.java
index eb4b801e8..935804942 100644
--- a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/TextureSamplerState.java
+++ b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/TextureSamplerState.java
@@ -1,6 +1,9 @@
 package com.gtnewhorizons.angelica.sdlgpu.resource;
 
+import org.lwjgl.opengl.EXTTextureFilterAnisotropic;
 import org.lwjgl.opengl.GL11;
+import org.lwjgl.opengl.GL12;
+import org.lwjgl.opengl.GL14;
 
 public final class TextureSamplerState {
     public int minFilter = GL11.GL_NEAREST_MIPMAP_LINEAR;
@@ -16,4 +19,37 @@ public final class TextureSamplerState {
     public int compareMode = 0;
     public int compareFunc = GL11.GL_LEQUAL;
     public long sdlSampler;
+
+    public boolean invalidate(boolean changed) {
+        if (!changed && sdlSampler != 0) return false;
+        sdlSampler = 0;
+        return true;
+    }
+
+    public boolean seti(int pname, int param) {
+        switch (pname) {
+            case GL11.GL_TEXTURE_MIN_FILTER -> { if (minFilter == param) return false; minFilter = param; }
+            case GL11.GL_TEXTURE_MAG_FILTER -> { if (magFilter == param) return false; magFilter = param; }
+            case GL11.GL_TEXTURE_WRAP_S -> { if (wrapS == param) return false; wrapS = param; }
+            case GL11.GL_TEXTURE_WRAP_T -> { if (wrapT == param) return false; wrapT = param; }
+            case GL12.GL_TEXTURE_WRAP_R -> { if (wrapR == param) return false; wrapR = param; }
+            case GL12.GL_TEXTURE_MAX_LEVEL -> { maxLevel = param; return false; }
+            case GL14.GL_TEXTURE_COMPARE_MODE -> { if (compareMode == param) return false; compareMode = param; }
+            case GL14.GL_TEXTURE_COMPARE_FUNC -> { if (compareFunc == param) return false; compareFunc = param; }
+            case GL12.GL_TEXTURE_MIN_LOD, GL12.GL_TEXTURE_MAX_LOD, EXTTextureFilterAnisotropic.GL_TEXTURE_MAX_ANISOTROPY_EXT -> { return setf(pname, (float) param); }
+            default -> { return false; }
+        }
+        return true;
+    }
+
+    public boolean setf(int pname, float param) {
+        switch (pname) {
+            case GL12.GL_TEXTURE_MIN_LOD -> { if (minLod == param) return false; minLod = param; }
+            case GL12.GL_TEXTURE_MAX_LOD -> { if (maxLod == param) return false; maxLod = param; }
+            case GL14.GL_TEXTURE_LOD_BIAS -> { if (lodBias == param) return false; lodBias = param; }
+            case EXTTextureFilterAnisotropic.GL_TEXTURE_MAX_ANISOTROPY_EXT -> { if (maxAnisotropy == param) return false; maxAnisotropy = param; }
+            default -> { return seti(pname, (int) param); }
+        }
+        return true;
+    }
 }
diff --git a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/TransferThread.java b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/TransferThread.java
index 51ddc15cb..3227b089b 100644
--- a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/TransferThread.java
+++ b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/resource/TransferThread.java
@@ -10,13 +10,15 @@ import org.lwjgl.sdl.SDL_GPUTransferBufferLocation;
 import org.lwjgl.sdl.SDLError;
 
 import java.nio.ByteBuffer;
-import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.ArrayDeque;
 import java.util.concurrent.atomic.AtomicLong;
 import java.util.concurrent.locks.LockSupport;
 
 import com.gtnewhorizons.angelica.glsm.profiling.Tracy;
+import com.gtnewhorizons.angelica.glsm.profiling.DebugCounters;
 import com.gtnewhorizons.angelica.glsm.profiling.TracyBackend;
 import com.gtnewhorizons.angelica.sdlgpu.device.Device;
+import com.gtnewhorizons.angelica.sdlgpu.device.Submits;
 import com.gtnewhorizons.angelica.sdlgpu.device.GpuDeviceLostException;
 import com.gtnewhorizons.angelica.sdlgpu.resource.ResourceManager;
 import it.unimi.dsi.fastutil.longs.LongArrayList;
@@ -44,7 +46,7 @@ public final class TransferThread {
     private final Device device;
     private final ResourceManager resourceManager;
     private final Thread thread;
-    private final ConcurrentLinkedQueue<DeferredUpload> queue = new ConcurrentLinkedQueue<>();
+    private final ArrayDeque<DeferredUpload> queue = new ArrayDeque<>();
     private volatile long submittedSeq;
     private volatile long flushRequestedSeq;
     private volatile boolean shutdown;
@@ -71,6 +73,7 @@ public final class TransferThread {
     private static final long FLUSH_COALESCE_BYTES = 8L * 1024 * 1024;
     private static final int FLUSH_COALESCE_COMMANDS = 128;
     private static final long WAKE_COALESCE_ENQUEUES = 16;
+    private static final long AWAIT_SPIN_NS = 30_000L;
 
     private long openCB;
     private long openCopyPass;
@@ -87,8 +90,8 @@ public final class TransferThread {
     private final SDL_GPUTextureTransferInfo texXferInfo = SDL_GPUTextureTransferInfo.calloc();
     private final SDL_GPUTextureRegion texRegion = SDL_GPUTextureRegion.calloc();
 
-    private static final ConcurrentLinkedQueue<PendingFree> FREE_POOL = new ConcurrentLinkedQueue<>();
-    private final ConcurrentLinkedQueue<PendingFree> pendingFrees = new ConcurrentLinkedQueue<>();
+    private final ArrayDeque<PendingFree> freePool = new ArrayDeque<>();
+    private final ArrayDeque<PendingFree> pendingFrees = new ArrayDeque<>();
 
     public TransferThread(Device device, ResourceManager resourceManager) {
         this.device = device;
@@ -103,10 +106,18 @@ public final class TransferThread {
     public long getSubmittedSeq() { return submittedSeq; }
 
     public void enqueue(DeferredUpload upload) {
-        queue.offer(upload);
+        synchronized (queue) { queue.addLast(upload); }
         if (shouldWakeOnEnqueue(upload.seq())) wake();
     }
 
+    private DeferredUpload pollUpload() {
+        synchronized (queue) { return queue.pollFirst(); }
+    }
+
+    private boolean queueEmpty() {
+        synchronized (queue) { return queue.isEmpty(); }
+    }
+
     static boolean shouldWakeOnEnqueue(long seq) {
         return (seq & (WAKE_COALESCE_ENQUEUES - 1)) == 0;
     }
@@ -123,32 +134,38 @@ public final class TransferThread {
     public void freeAfterSeq(ByteBuffer buf, long seq) {
         if (buf == null) return;
         if (seq <= submittedSeq) { MemoryUtil.memFree(buf); return; }
-        PendingFree pf = FREE_POOL.poll();
-        if (pf == null) pf = new PendingFree();
-        pf.seq = seq;
-        pf.buf = buf;
-        pendingFrees.offer(pf);
+        synchronized (pendingFrees) {
+            PendingFree pf = freePool.pollLast();
+            if (pf == null) pf = new PendingFree();
+            pf.seq = seq;
+            pf.buf = buf;
+            pendingFrees.addLast(pf);
+        }
         wake();
     }
 
     private void drainDuePendingFrees() {
         final long sub = submittedSeq;
-        PendingFree head = pendingFrees.peek();
-        while (head != null && head.seq <= sub) {
-            pendingFrees.poll();
-            MemoryUtil.memFree(head.buf);
-            head.buf = null;
-            FREE_POOL.offer(head);
-            head = pendingFrees.peek();
+        synchronized (pendingFrees) {
+            PendingFree head = pendingFrees.peekFirst();
+            while (head != null && head.seq <= sub) {
+                pendingFrees.pollFirst();
+                MemoryUtil.memFree(head.buf);
+                head.buf = null;
+                freePool.addLast(head);
+                head = pendingFrees.peekFirst();
+            }
         }
     }
 
     private void drainAllPendingFreesOnShutdown() {
-        PendingFree pf;
-        while ((pf = pendingFrees.poll()) != null) {
-            MemoryUtil.memFree(pf.buf);
-            pf.buf = null;
-            FREE_POOL.offer(pf);
+        synchronized (pendingFrees) {
+            PendingFree pf;
+            while ((pf = pendingFrees.pollFirst()) != null) {
+                MemoryUtil.memFree(pf.buf);
+                pf.buf = null;
+                freePool.addLast(pf);
+            }
         }
     }
 
@@ -165,19 +182,31 @@ public final class TransferThread {
         if (seq > flushRequestedSeq) flushRequestedSeq = seq;
         LockSupport.unpark(thread);
         final long startNs = System.nanoTime();
-        synchronized (submittedLock) {
-            while (submittedSeq < seq) {
-                try {
-                    submittedLock.wait();
-                } catch (InterruptedException e) {
-                    Thread.currentThread().interrupt();
-                    break;
+        if (!spinUntilSubmitted(seq)) {
+            synchronized (submittedLock) {
+                while (submittedSeq < seq) {
+                    try {
+                        submittedLock.wait();
+                    } catch (InterruptedException e) {
+                        Thread.currentThread().interrupt();
+                        break;
+                    }
                 }
             }
         }
         final long waitNs = System.nanoTime() - startNs;
         if (waitNs > maxWaitNs) maxWaitNs = waitNs;
         pendingFrameWaitNanos += waitNs;
+        DebugCounters.TRANSFER_WAIT_NANOS.add(waitNs);
+    }
+
+    private boolean spinUntilSubmitted(long seq) {
+        final long start = System.nanoTime();
+        while (submittedSeq < seq) {
+            if (System.nanoTime() - start >= AWAIT_SPIN_NS) return false;
+            Thread.onSpinWait();
+        }
+        return true;
     }
 
     public void shutdown() {
@@ -234,11 +263,11 @@ public final class TransferThread {
             while (!shutdown) {
                 final long workStart = Tracy.ENABLED ? System.nanoTime() : 0L;
                 // Drain all pending uploads
-                DeferredUpload upload = queue.poll();
+                DeferredUpload upload = pollUpload();
                 if (upload != null) {
                     do {
                         processOne(upload);
-                        upload = queue.poll();
+                        upload = pollUpload();
                     } while (upload != null);
                 }
 
@@ -251,9 +280,9 @@ public final class TransferThread {
 
                 if (Tracy.ENABLED) pendingActiveNanos += System.nanoTime() - workStart;
 
-                if (queue.isEmpty() && !shutdown) {
+                if (queueEmpty() && !shutdown) {
                     parked = true;
-                    if (queue.isEmpty() && !shutdown && flushRequestedSeq <= submittedSeq) {
+                    if (queueEmpty() && !shutdown && flushRequestedSeq <= submittedSeq) {
                         LockSupport.parkNanos(1_000_000L); // 1ms
                     }
                     parked = false;
@@ -405,7 +434,7 @@ public final class TransferThread {
         if (openCB == 0) return;
 
         SDL_EndGPUCopyPass(openCopyPass);
-        if (!SDL_SubmitGPUCommandBuffer(openCB)) {
+        if (!Submits.submit(openCB)) {
             device.reportGpuFailure("submit transfer command buffer");
         }
 
@@ -459,7 +488,7 @@ public final class TransferThread {
     }
 
     public static final class StagingReadUpload implements DeferredUpload {
-        private static final ConcurrentLinkedQueue<StagingReadUpload> POOL = new ConcurrentLinkedQueue<>();
+        private static final ArrayDeque<StagingReadUpload> POOL = new ArrayDeque<>();
 
         public ByteBuffer stagingBuffer;
         public long srcOffset;
@@ -471,8 +500,8 @@ public final class TransferThread {
 
         private StagingReadUpload() {}
 
-        public static StagingReadUpload acquire(ByteBuffer stagingBuffer, long srcOffset, long size, long dstGpuBuffer, long dstOffset, long seq, boolean cycle) {
-            StagingReadUpload obj = POOL.poll();
+        public static synchronized StagingReadUpload acquire(ByteBuffer stagingBuffer, long srcOffset, long size, long dstGpuBuffer, long dstOffset, long seq, boolean cycle) {
+            StagingReadUpload obj = POOL.pollLast();
             if (obj == null) obj = new StagingReadUpload();
             obj.stagingBuffer = stagingBuffer;
             obj.srcOffset = srcOffset;
@@ -484,16 +513,16 @@ public final class TransferThread {
             return obj;
         }
 
-        public static void release(StagingReadUpload obj) {
+        public static synchronized void release(StagingReadUpload obj) {
             obj.stagingBuffer = null;
-            POOL.offer(obj);
+            POOL.addLast(obj);
         }
 
         @Override public long seq() { return seq; }
     }
 
     public static final class PreCopiedUpload implements DeferredUpload {
-        private static final ConcurrentLinkedQueue<PreCopiedUpload> POOL = new ConcurrentLinkedQueue<>();
+        private static final ArrayDeque<PreCopiedUpload> POOL = new ArrayDeque<>();
 
         public long transferBuffer;
         public long size;
@@ -504,8 +533,8 @@ public final class TransferThread {
 
         private PreCopiedUpload() {}
 
-        public static PreCopiedUpload acquire(long transferBuffer, long size, long dstGpuBuffer, long dstOffset, long seq, boolean cycle) {
-            PreCopiedUpload obj = POOL.poll();
+        public static synchronized PreCopiedUpload acquire(long transferBuffer, long size, long dstGpuBuffer, long dstOffset, long seq, boolean cycle) {
+            PreCopiedUpload obj = POOL.pollLast();
             if (obj == null) obj = new PreCopiedUpload();
             obj.transferBuffer = transferBuffer;
             obj.size = size;
@@ -516,15 +545,15 @@ public final class TransferThread {
             return obj;
         }
 
-        public static void release(PreCopiedUpload obj) {
-            POOL.offer(obj);
+        public static synchronized void release(PreCopiedUpload obj) {
+            POOL.addLast(obj);
         }
 
         @Override public long seq() { return seq; }
     }
 
     public static final class GpuCopyUpload implements DeferredUpload {
-        private static final ConcurrentLinkedQueue<GpuCopyUpload> POOL = new ConcurrentLinkedQueue<>();
+        private static final ArrayDeque<GpuCopyUpload> POOL = new ArrayDeque<>();
 
         public long srcHandle;
         public long dstHandle;
@@ -535,9 +564,9 @@ public final class TransferThread {
 
         private GpuCopyUpload() {}
 
-        public static GpuCopyUpload acquire(long srcHandle, long dstHandle, long readOffset,
+        public static synchronized GpuCopyUpload acquire(long srcHandle, long dstHandle, long readOffset,
                                      long writeOffset, long size, long seq) {
-            GpuCopyUpload obj = POOL.poll();
+            GpuCopyUpload obj = POOL.pollLast();
             if (obj == null) obj = new GpuCopyUpload();
             obj.srcHandle = srcHandle;
             obj.dstHandle = dstHandle;
@@ -548,15 +577,15 @@ public final class TransferThread {
             return obj;
         }
 
-        public static void release(GpuCopyUpload obj) {
-            POOL.offer(obj);
+        public static synchronized void release(GpuCopyUpload obj) {
+            POOL.addLast(obj);
         }
 
         @Override public long seq() { return seq; }
     }
 
     public static final class TextureRegionUpload implements DeferredUpload {
-        private static final ConcurrentLinkedQueue<TextureRegionUpload> POOL = new ConcurrentLinkedQueue<>();
+        private static final ArrayDeque<TextureRegionUpload> POOL = new ArrayDeque<>();
 
         public long transferBuffer;
         public long texHandle;
@@ -570,8 +599,8 @@ public final class TransferThread {
 
         private TextureRegionUpload() {}
 
-        public static TextureRegionUpload acquire(long transferBuffer, long texHandle, int x, int y, int w, int h, int level, long size, long seq) {
-            TextureRegionUpload obj = POOL.poll();
+        public static synchronized TextureRegionUpload acquire(long transferBuffer, long texHandle, int x, int y, int w, int h, int level, long size, long seq) {
+            TextureRegionUpload obj = POOL.pollLast();
             if (obj == null) obj = new TextureRegionUpload();
             obj.transferBuffer = transferBuffer;
             obj.texHandle = texHandle;
@@ -585,8 +614,8 @@ public final class TransferThread {
             return obj;
         }
 
-        public static void release(TextureRegionUpload obj) {
-            POOL.offer(obj);
+        public static synchronized void release(TextureRegionUpload obj) {
+            POOL.addLast(obj);
         }
 
         @Override public long seq() { return seq; }
diff --git a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/sampler/SamplerBinder.java b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/sampler/SamplerBinder.java
index fd7204cb2..05458f151 100644
--- a/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/sampler/SamplerBinder.java
+++ b/sdl-gpu/src/main/java/com/gtnewhorizons/angelica/sdlgpu/sampler/SamplerBinder.java
@@ -28,6 +28,7 @@ public final class SamplerBinder {
     private final Device device;
     private final ResourceManager resourceManager;
     private final ShaderManager shaderManager;
+    private final SamplerCache.Factory samplerFactory = this::createSamplerForKey;
 
     public SamplerBinder(Device device, ResourceManager resourceManager, ShaderManager shaderManager) {
         this.device = device;
@@ -58,7 +59,7 @@ public final class SamplerBinder {
             ss.minLod, ss.maxLod, ss.lodBias,
             ss.maxAnisotropy, ss.compareMode, ss.compareFunc);
 
-        final long handle = resourceManager.samplerCache().getOrCreate(key, this::createSamplerForKey);
+        final long handle = resourceManager.samplerCache().getOrCreate(key, samplerFactory);
         ss.sdlSampler = handle;
         return handle != 0 ? handle : resourceManager.getOrCreateDefaultSampler();
     }
diff --git a/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/SdlTestRig.java b/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/SdlTestRig.java
index d1f90ba78..9e97acc5c 100644
--- a/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/SdlTestRig.java
+++ b/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/SdlTestRig.java
@@ -14,6 +14,7 @@ import java.lang.reflect.Field;
 import static org.junit.jupiter.api.Assumptions.assumeTrue;
 import static org.lwjgl.sdl.SDLGPU.SDL_CreateGPUDevice;
 import static org.lwjgl.sdl.SDLGPU.SDL_DestroyGPUDevice;
+import static org.lwjgl.sdl.SDLGPU.SDL_GetGPUDeviceDriver;
 import static org.lwjgl.sdl.SDLGPU.SDL_GetGPUShaderFormats;
 import static org.lwjgl.sdl.SDLGPU.SDL_GPU_SHADERFORMAT_DXBC;
 import static org.lwjgl.sdl.SDLGPU.SDL_GPU_SHADERFORMAT_DXIL;
@@ -21,6 +22,7 @@ import static org.lwjgl.sdl.SDLGPU.SDL_GPU_SHADERFORMAT_MSL;
 import static org.lwjgl.sdl.SDLGPU.SDL_GPU_SHADERFORMAT_SPIRV;
 import static org.lwjgl.sdl.SDLGPU.SDL_WaitForGPUIdle;
 import static org.lwjgl.sdl.SDLInit.SDL_INIT_VIDEO;
+import static org.lwjgl.sdl.SDLVersion.SDL_GetVersion;
 
 public final class SdlTestRig {
 
@@ -39,6 +41,8 @@ public final class SdlTestRig {
             final Field formatsField = Device.class.getDeclaredField("supportedShaderFormats");
             formatsField.setAccessible(true);
             formatsField.setInt(this.device, SDL_GetGPUShaderFormats(sdlHandle));
+            Reflect.set(this.device, "driverName", SDL_GetGPUDeviceDriver(sdlHandle));
+            Reflect.invoke(this.device, "probeFences", new Class<?>[] { int.class }, SDL_GetVersion());
         }
         this.frameManager = new FrameManager(device);
         this.resourceManager = new ResourceManager(device, frameManager);
diff --git a/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/device/FenceProbeRealDeviceTest.java b/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/device/FenceProbeRealDeviceTest.java
new file mode 100644
index 000000000..f038c4733
--- /dev/null
+++ b/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/device/FenceProbeRealDeviceTest.java
@@ -0,0 +1,50 @@
+package com.gtnewhorizons.angelica.sdlgpu.device;
+
+import com.gtnewhorizons.angelica.sdlgpu.SdlTestRig;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.lwjgl.system.MemoryStack;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.lwjgl.sdl.SDLGPU.SDL_AcquireGPUCommandBuffer;
+import static org.lwjgl.sdl.SDLGPU.SDL_GetGPUDeviceDriver;
+import static org.lwjgl.sdl.SDLGPU.SDL_ReleaseGPUFence;
+import static org.lwjgl.sdl.SDLGPU.SDL_SubmitGPUCommandBufferAndAcquireFence;
+import static org.lwjgl.sdl.SDLGPU.SDL_WaitForGPUFences;
+import static org.lwjgl.sdl.SDLVersion.SDL_GetVersion;
+import static org.lwjgl.sdl.SDLVersion.SDL_VERSIONNUM;
+
+class FenceProbeRealDeviceTest {
+
+    private static SdlTestRig rig;
+
+    @BeforeAll
+    static void setUp() throws Exception {
+        rig = SdlTestRig.acquireRealDevice();
+    }
+
+    @AfterAll
+    static void tearDown() {
+        SdlTestRig.releaseRealDevice();
+    }
+
+    @Test
+    void probeMatchesVersionTableAndCorrectedQueryReadsSignaled() {
+        final String driver = SDL_GetGPUDeviceDriver(rig.sdlHandle);
+        assertEquals("metal".equalsIgnoreCase(driver) && SDL_GetVersion() == SDL_VERSIONNUM(3, 4, 14), rig.device.isFenceQueryInverted(), "driver=" + driver + " sdl=" + SDL_GetVersion());
+
+        final long cb = SDL_AcquireGPUCommandBuffer(rig.sdlHandle);
+        assertNotEquals(0L, cb);
+        final long fence = SDL_SubmitGPUCommandBufferAndAcquireFence(cb);
+        assertNotEquals(0L, fence);
+        try (MemoryStack stack = MemoryStack.stackPush()) {
+            assertTrue(SDL_WaitForGPUFences(rig.sdlHandle, true, stack.pointers(fence)));
+            assertTrue(FenceWait.isSignaled(rig.device, fence));
+        } finally {
+            SDL_ReleaseGPUFence(rig.sdlHandle, fence);
+        }
+    }
+}
diff --git a/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/device/FenceReleaserTest.java b/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/device/FenceReleaserTest.java
new file mode 100644
index 000000000..a63a46c7c
--- /dev/null
+++ b/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/device/FenceReleaserTest.java
@@ -0,0 +1,88 @@
+package com.gtnewhorizons.angelica.sdlgpu.device;
+
+import it.unimi.dsi.fastutil.longs.LongArrayList;
+import it.unimi.dsi.fastutil.longs.LongOpenHashSet;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class FenceReleaserTest {
+
+    private static final class FakeOps {
+        final LongOpenHashSet signaled = new LongOpenHashSet();
+        final LongArrayList released = new LongArrayList();
+
+        FenceReleaser releaser() { return new FenceReleaser(signaled::contains, released::add); }
+    }
+
+    @Test
+    void signaledFenceIsReleasedImmediately() {
+        final FakeOps ops = new FakeOps();
+        final FenceReleaser r = ops.releaser();
+        ops.signaled.add(7L);
+        r.release(7L);
+        assertEquals(LongArrayList.of(7L), ops.released);
+    }
+
+    @Test
+    void zeroFenceIsIgnored() {
+        final FakeOps ops = new FakeOps();
+        final FenceReleaser r = ops.releaser();
+        r.release(0L);
+        r.releaseAll();
+        assertTrue(ops.released.isEmpty());
+    }
+
+    @Test
+    void unsignaledFencePendsUntilDrainSeesItSignaled() {
+        final FakeOps ops = new FakeOps();
+        final FenceReleaser r = ops.releaser();
+        r.release(1L);
+        r.release(2L);
+        r.release(3L);
+        assertTrue(ops.released.isEmpty());
+        r.drain();
+        assertTrue(ops.released.isEmpty());
+        ops.signaled.add(2L);
+        r.drain();
+        assertEquals(LongArrayList.of(2L), ops.released);
+        r.drain();
+        assertEquals(LongArrayList.of(2L), ops.released);
+    }
+
+    @Test
+    void drainReleasesEverySignaledFenceExactlyOnce() {
+        final FakeOps ops = new FakeOps();
+        final FenceReleaser r = ops.releaser();
+        for (long f = 1; f <= 5; f++) r.release(f);
+        ops.signaled.add(1L);
+        ops.signaled.add(3L);
+        ops.signaled.add(5L);
+        r.drain();
+        assertEquals(new LongOpenHashSet(new long[]{1L, 3L, 5L}), new LongOpenHashSet(ops.released));
+        assertEquals(3, ops.released.size());
+        ops.signaled.add(2L);
+        ops.signaled.add(4L);
+        r.drain();
+        r.drain();
+        assertEquals(new LongOpenHashSet(new long[]{1L, 2L, 3L, 4L, 5L}), new LongOpenHashSet(ops.released));
+        assertEquals(5, ops.released.size());
+    }
+
+    @Test
+    void releaseAllEmptiesPendingWithoutDoubleRelease() {
+        final FakeOps ops = new FakeOps();
+        final FenceReleaser r = ops.releaser();
+        r.release(1L);
+        r.release(2L);
+        ops.signaled.add(1L);
+        r.drain();
+        r.releaseAll();
+        assertEquals(LongArrayList.of(1L, 2L), ops.released);
+        ops.signaled.add(2L);
+        r.drain();
+        r.releaseAll();
+        assertEquals(LongArrayList.of(1L, 2L), ops.released);
+    }
+}
diff --git a/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/device/FenceWaitTest.java b/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/device/FenceWaitTest.java
new file mode 100644
index 000000000..2248f6cc7
--- /dev/null
+++ b/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/device/FenceWaitTest.java
@@ -0,0 +1,141 @@
+package com.gtnewhorizons.angelica.sdlgpu.device;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.lwjgl.sdl.SDLVersion.SDL_VERSIONNUM;
+
+class FenceWaitTest {
+
+    private static final class FakeOps implements FenceWait.Ops {
+        long now;
+        long signalAt = Long.MAX_VALUE;
+        long tick = 1_000L;
+        int queries;
+        int nativeWaits;
+        int parks;
+        long parkedNs;
+        long maxPark;
+        long firstParkAt = -1;
+
+        @Override public boolean query(long dev, long fence) {
+            queries++;
+            return now >= signalAt;
+        }
+
+        @Override public void waitNative(long dev, long fence) {
+            nativeWaits++;
+            now = Math.max(now, signalAt);
+        }
+
+        @Override public long nanoTime() {
+            now += tick;
+            return now;
+        }
+
+        @Override public void park(long nanos) {
+            assertTrue(nanos > 0, "park must never be asked for a non-positive duration");
+            if (firstParkAt < 0) firstParkAt = now;
+            parks++;
+            parkedNs += nanos;
+            maxPark = Math.max(maxPark, nanos);
+            now += nanos;
+        }
+    }
+
+    @Test
+    void alreadySignalledReturnsWithoutWaiting() {
+        final FakeOps ops = new FakeOps();
+        ops.signalAt = 0;
+        assertTrue(FenceWait.await(1L, 2L, FenceWait.FOREVER, true, ops));
+        assertEquals(1, ops.queries);
+        assertEquals(0, ops.parks);
+        assertEquals(0, ops.nativeWaits);
+    }
+
+    @Test
+    void zeroTimeoutIsAPureQuery() {
+        final FakeOps ops = new FakeOps();
+        assertFalse(FenceWait.await(1L, 2L, 0L, true, ops));
+        assertEquals(1, ops.queries);
+        assertEquals(0, ops.parks);
+    }
+
+    @Test
+    void spinsBeforeParkingThenParksInBoundedSlices() {
+        final FakeOps ops = new FakeOps();
+        ops.signalAt = 500_000L;
+        assertTrue(FenceWait.await(1L, 2L, FenceWait.FOREVER, true, ops));
+        assertTrue(ops.firstParkAt >= FenceWait.SPIN_NS, "must spin for the first " + FenceWait.SPIN_NS + "ns, parked at " + ops.firstParkAt);
+        assertTrue(ops.parks > 0);
+        assertEquals(FenceWait.PARK_MAX_NS, ops.maxPark);
+        assertEquals(0, ops.nativeWaits);
+    }
+
+    @Test
+    void signalDuringSpinNeverParks() {
+        final FakeOps ops = new FakeOps();
+        ops.signalAt = 5_000L;
+        assertTrue(FenceWait.await(1L, 2L, FenceWait.FOREVER, true, ops));
+        assertEquals(0, ops.parks);
+    }
+
+    @Test
+    void finiteTimeoutExpiresWithoutOvershootingTheDeadline() {
+        final FakeOps ops = new FakeOps();
+        final long timeout = 130_000L;
+        final long start = ops.now;
+        assertFalse(FenceWait.await(1L, 2L, timeout, true, ops));
+        final long elapsed = ops.now - start;
+        assertTrue(elapsed >= timeout, "returned early: " + elapsed);
+        assertTrue(elapsed <= timeout + 2 * ops.tick, "last park must be clamped to the remaining time: " + elapsed);
+    }
+
+    @Test
+    void finiteTimeoutPollsWhenForeverPollingIsDisabled() {
+        final FakeOps ops = new FakeOps();
+        ops.signalAt = 60_000L;
+        assertTrue(FenceWait.await(1L, 2L, 100_000L, false, ops));
+        assertEquals(0, ops.nativeWaits, "a finite timeout must poll on every backend so it can expire");
+        assertTrue(ops.parks > 0);
+    }
+
+    @Test
+    void interruptFlagSurvivesAPollingWait() {
+        final FakeOps ops = new FakeOps();
+        ops.signalAt = 500_000L;
+        Thread.currentThread().interrupt();
+        assertTrue(FenceWait.await(1L, 2L, FenceWait.FOREVER, true, ops));
+        assertTrue(ops.parks > 0);
+        assertTrue(Thread.interrupted(), "the caller's interrupt must be restored");
+    }
+
+    @Test
+    void foreverWithoutPollingUsesTheNativeWait() {
+        final FakeOps ops = new FakeOps();
+        ops.signalAt = 1_000_000L;
+        assertTrue(FenceWait.await(1L, 2L, FenceWait.FOREVER, false, ops));
+        assertEquals(1, ops.nativeWaits);
+        assertEquals(0, ops.parks);
+    }
+
+    @Test
+    void timeoutIgnoredIsForever() {
+        final FakeOps ops = new FakeOps();
+        ops.signalAt = 1_000_000L;
+        assertTrue(FenceWait.await(1L, 2L, -1L, false, ops));
+        assertEquals(1, ops.nativeWaits);
+    }
+
+    @Test
+    void pollingOnlyOnMetalWhileItsWaitSpins() {
+        assertTrue(FenceWait.pollEnabled("metal", SDL_VERSIONNUM(3, 4, 12)));
+        assertFalse(FenceWait.pollEnabled("metal", SDL_VERSIONNUM(3, 4, 14)));
+        assertFalse(FenceWait.pollEnabled("metal", SDL_VERSIONNUM(3, 5, 0)));
+        assertFalse(FenceWait.pollEnabled("vulkan", SDL_VERSIONNUM(3, 4, 12)));
+        assertFalse(FenceWait.pollEnabled("direct3d12", SDL_VERSIONNUM(3, 4, 12)));
+        assertFalse(FenceWait.pollEnabled(null, SDL_VERSIONNUM(3, 4, 12)));
+    }
+}
diff --git a/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/frame/PresenterTest.java b/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/frame/PresenterTest.java
index 5e9e9d338..3b604b77f 100644
--- a/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/frame/PresenterTest.java
+++ b/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/frame/PresenterTest.java
@@ -1,5 +1,6 @@
 package com.gtnewhorizons.angelica.sdlgpu.frame;
 
+import com.gtnewhorizons.angelica.glsm.backend.MainThreadPump;
 import com.gtnewhorizons.angelica.sdlgpu.device.Device;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.Timeout;
@@ -7,15 +8,23 @@ import org.junit.jupiter.api.Timeout;
 import java.util.ArrayDeque;
 import java.util.Deque;
 import java.util.concurrent.Executor;
+import java.util.concurrent.RejectedExecutionException;
+import java.util.concurrent.atomic.AtomicInteger;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.lwjgl.sdl.SDLSurface.SDL_FLIP_NONE;
 
 @Timeout(10)
 class PresenterTest {
 
+    private static MainThreadPump noPump() {
+        return new MainThreadPump(Runnable::run, () -> true, () -> {}, () -> {});
+    }
+
     private static final class DeferredExecutor implements Executor {
         final Deque<Runnable> tasks = new ArrayDeque<>();
 
@@ -30,7 +39,7 @@ class PresenterTest {
     }
 
     private static Presenter presenter(DeferredExecutor executor) {
-        return new Presenter(new FrameManager(new Device()), executor);
+        return new Presenter(new FrameManager(new Device()), executor, noPump());
     }
 
     private static void awaitWaiting(Thread t) throws InterruptedException {
@@ -90,7 +99,7 @@ class PresenterTest {
 
     @Test
     void anInlineExecutorReleasesTheSlotImmediately() {
-        final Presenter p = new Presenter(new FrameManager(new Device()), Runnable::run);
+        final Presenter p = new Presenter(new FrameManager(new Device()), Runnable::run, noPump());
         p.requestPresent(1L, 10, 10, SDL_FLIP_NONE);
         p.requestPresent(2L, 10, 10, SDL_FLIP_NONE);
         p.drain();
@@ -100,7 +109,7 @@ class PresenterTest {
     void presentingDoesNotEnterTheFrameRegistry() throws Exception {
         final DeferredExecutor executor = new DeferredExecutor();
         final FrameManager fm = new FrameManager(new Device());
-        final Presenter p = new Presenter(fm, executor);
+        final Presenter p = new Presenter(fm, executor, noPump());
         fm.frame();
         final int before = fm.registeredFrameCount();
 
@@ -117,7 +126,7 @@ class PresenterTest {
     void theSplashPresentGoesThroughTheWindowThreadToo() {
         final DeferredExecutor executor = new DeferredExecutor();
         final FrameManager fm = new FrameManager(new Device());
-        fm.setPresenter(new Presenter(fm, executor));
+        fm.setPresenter(new Presenter(fm, executor, noPump()));
         fm.frame();
         final int before = fm.registeredFrameCount();
 
@@ -126,4 +135,94 @@ class PresenterTest {
         assertEquals(1, executor.tasks.size(), "the splash blit must be enqueued on the window thread");
         assertEquals(before, fm.registeredFrameCount(), "the splash present must not touch the calling thread's frame");
     }
+
+    @Test
+    void tryRequestEnqueuesWhenIdle() {
+        final DeferredExecutor executor = new DeferredExecutor();
+        final Presenter p = presenter(executor);
+
+        assertTrue(p.tryRequestPresent(1L, 10, 10, SDL_FLIP_NONE));
+        assertEquals(1, executor.tasks.size());
+    }
+
+    @Test
+    void tryRequestDropsWithoutBlockingWhileAPresentIsPending() {
+        final DeferredExecutor executor = new DeferredExecutor();
+        final Presenter p = presenter(executor);
+
+        p.requestPresent(1L, 10, 10, SDL_FLIP_NONE);
+        assertFalse(p.tryRequestPresent(2L, 10, 10, SDL_FLIP_NONE));
+        assertEquals(1, executor.tasks.size(), "a dropped present must not enqueue");
+
+        executor.runNext();
+        assertTrue(p.tryRequestPresent(3L, 10, 10, SDL_FLIP_NONE));
+        assertEquals(1, executor.tasks.size());
+    }
+
+    @Test
+    void drainBlocksUntilAnAcceptedTryRequestRuns() throws Exception {
+        final DeferredExecutor executor = new DeferredExecutor();
+        final Presenter p = presenter(executor);
+
+        assertTrue(p.tryRequestPresent(1L, 10, 10, SDL_FLIP_NONE));
+
+        final Thread drainer = new Thread(p::drain);
+        drainer.start();
+        awaitWaiting(drainer);
+
+        executor.runNext();
+        drainer.join();
+    }
+
+    @Test
+    void aBlockingRequestWaitsBehindAnAcceptedTryRequest() throws Exception {
+        final DeferredExecutor executor = new DeferredExecutor();
+        final Presenter p = presenter(executor);
+
+        assertTrue(p.tryRequestPresent(1L, 10, 10, SDL_FLIP_NONE));
+
+        final Thread second = new Thread(() -> p.requestPresent(2L, 10, 10, SDL_FLIP_NONE));
+        second.start();
+        awaitWaiting(second);
+        assertEquals(1, executor.tasks.size());
+
+        executor.runNext();
+        second.join();
+        assertEquals(1, executor.tasks.size());
+    }
+
+    @Test
+    void thePresentTaskPumpsFirstAndEndsThePresentWindow() throws Exception {
+        final DeferredExecutor executor = new DeferredExecutor();
+        final AtomicInteger pumps = new AtomicInteger();
+        final MainThreadPump pump = new MainThreadPump(Runnable::run, () -> false, pumps::incrementAndGet, () -> {});
+        final Presenter p = new Presenter(new FrameManager(new Device()), executor, pump);
+
+        p.requestPresent(1L, 10, 10, SDL_FLIP_NONE);
+        final Thread client = new Thread(pump::pumpMessages, "client");
+        client.start();
+        awaitWaiting(client);
+        assertEquals(0, pumps.get(), "a client pump must wait for the present task's pump, not run its own");
+
+        executor.runNext();
+        client.join();
+        final int afterPresent = pumps.get();
+        assertTrue(afterPresent >= 1, "the present task must pump");
+
+        pump.pumpMessages();
+        assertEquals(afterPresent + 1, pumps.get(), "after the present ends, client pumps run normally again");
+    }
+
+    @Test
+    void aRejectedSubmitEndsThePresentWindowAndReleasesTheSlot() {
+        final AtomicInteger pumps = new AtomicInteger();
+        final MainThreadPump pump = new MainThreadPump(Runnable::run, () -> false, pumps::incrementAndGet, () -> {});
+        final Presenter p = new Presenter(new FrameManager(new Device()), r -> { throw new RejectedExecutionException(); }, pump);
+
+        assertThrows(RejectedExecutionException.class, () -> p.requestPresent(1L, 10, 10, SDL_FLIP_NONE));
+
+        pump.pumpMessages();
+        assertEquals(1, pumps.get());
+        assertThrows(RejectedExecutionException.class, () -> p.tryRequestPresent(2L, 10, 10, SDL_FLIP_NONE));
+    }
 }
diff --git a/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/resource/TextureSamplerStateTest.java b/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/resource/TextureSamplerStateTest.java
new file mode 100644
index 000000000..5d1a77258
--- /dev/null
+++ b/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/resource/TextureSamplerStateTest.java
@@ -0,0 +1,52 @@
+package com.gtnewhorizons.angelica.sdlgpu.resource;
+
+import org.junit.jupiter.api.Test;
+import org.lwjgl.opengl.GL11;
+import org.lwjgl.opengl.GL12;
+import org.lwjgl.opengl.GL14;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class TextureSamplerStateTest {
+
+    @Test
+    void changedIntValueReportsChange() {
+        final TextureSamplerState ss = new TextureSamplerState();
+        assertTrue(ss.seti(GL11.GL_TEXTURE_MIN_FILTER, GL11.GL_LINEAR));
+        assertEquals(GL11.GL_LINEAR, ss.minFilter);
+        assertFalse(ss.seti(GL11.GL_TEXTURE_MIN_FILTER, GL11.GL_LINEAR));
+    }
+
+    @Test
+    void changedFloatValueReportsChange() {
+        final TextureSamplerState ss = new TextureSamplerState();
+        assertTrue(ss.setf(GL14.GL_TEXTURE_LOD_BIAS, 0.5f));
+        assertEquals(0.5f, ss.lodBias);
+        assertFalse(ss.setf(GL14.GL_TEXTURE_LOD_BIAS, 0.5f));
+    }
+
+    @Test
+    void setfFallsThroughToIntPname() {
+        final TextureSamplerState ss = new TextureSamplerState();
+        assertTrue(ss.setf(GL11.GL_TEXTURE_MIN_FILTER, (float) GL11.GL_LINEAR));
+        assertEquals(GL11.GL_LINEAR, ss.minFilter);
+        assertFalse(ss.setf(GL11.GL_TEXTURE_MIN_FILTER, (float) GL11.GL_LINEAR));
+    }
+
+    @Test
+    void setiRoutesLodToTheFloatField() {
+        final TextureSamplerState ss = new TextureSamplerState();
+        assertTrue(ss.seti(GL12.GL_TEXTURE_MIN_LOD, 2));
+        assertEquals(2.0f, ss.minLod);
+        assertFalse(ss.seti(GL12.GL_TEXTURE_MIN_LOD, 2));
+    }
+
+    @Test
+    void maxLevelIsStoredButNeverAffectsTheSampler() {
+        final TextureSamplerState ss = new TextureSamplerState();
+        assertFalse(ss.seti(GL12.GL_TEXTURE_MAX_LEVEL, 3));
+        assertEquals(3, ss.maxLevel);
+    }
+}
diff --git a/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/resource/TransferThreadWakePolicyTest.java b/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/resource/TransferThreadWakePolicyTest.java
index c874719f0..5549f2961 100644
--- a/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/resource/TransferThreadWakePolicyTest.java
+++ b/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/resource/TransferThreadWakePolicyTest.java
@@ -1,9 +1,14 @@
 package com.gtnewhorizons.angelica.sdlgpu.resource;
 
+import com.gtnewhorizons.angelica.glsm.testutil.Reflect;
+import com.gtnewhorizons.angelica.sdlgpu.SdlTestRig;
 import org.junit.jupiter.api.Test;
 
+import java.util.concurrent.locks.LockSupport;
+
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertSame;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 class TransferThreadWakePolicyTest {
@@ -43,4 +48,41 @@ class TransferThreadWakePolicyTest {
         }
         assertEquals(100, woken);
     }
+
+    private static TransferThread stoppedThread(long submittedSeq) {
+        final SdlTestRig rig = SdlTestRig.create();
+        final TransferThread tt = new TransferThread(rig.device, rig.resourceManager);
+        tt.shutdown();
+        try {
+            tt.getThread().join(5_000L);
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+            throw new AssertionError(e);
+        }
+        assertFalse(tt.getThread().isAlive());
+        Reflect.set(tt, "submittedSeq", submittedSeq);
+        return tt;
+    }
+
+    @Test
+    void awaitFallsBackToTheLockWhenSpinExpires() throws InterruptedException {
+        final TransferThread tt = stoppedThread(5L);
+        final Thread waiter = new Thread(() -> tt.awaitSubmittedUpTo(10L));
+        waiter.start();
+        LockSupport.parkNanos(20_000_000L);
+        assertTrue(waiter.isAlive(), "must still be blocked; nothing published");
+        Reflect.set(tt, "openHighestSeq", 10L);
+        Reflect.invoke(tt, "publishSubmittedSeq", new Class<?>[0]);
+        waiter.join(5_000L);
+        assertFalse(waiter.isAlive(), "publish must release a waiter parked on submittedLock");
+    }
+
+    @Test
+    void releasedUploadIsReusedByTheNextAcquire() {
+        final TransferThread.StagingReadUpload a = TransferThread.StagingReadUpload.acquire(null, 0L, 0L, 0L, 0L, 1L, false);
+        TransferThread.StagingReadUpload.release(a);
+        final TransferThread.StagingReadUpload b = TransferThread.StagingReadUpload.acquire(null, 0L, 0L, 0L, 0L, 2L, false);
+        assertSame(a, b);
+        TransferThread.StagingReadUpload.release(b);
+    }
 }
diff --git a/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/sampler/SamplerBindGenerationTest.java b/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/sampler/SamplerBindGenerationTest.java
index 741f4dcaf..a510e2053 100644
--- a/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/sampler/SamplerBindGenerationTest.java
+++ b/sdl-gpu/src/test/java/com/gtnewhorizons/angelica/sdlgpu/sampler/SamplerBindGenerationTest.java
@@ -1,8 +1,10 @@
 package com.gtnewhorizons.angelica.sdlgpu.sampler;
 
+import com.gtnewhorizons.angelica.glsm.testutil.Reflect;
 import com.gtnewhorizons.angelica.sdlgpu.SDLGPURenderBackend;
 import com.gtnewhorizons.angelica.sdlgpu.SdlTestRig;
 import com.gtnewhorizons.angelica.sdlgpu.frame.ContextState;
+import com.gtnewhorizons.angelica.sdlgpu.resource.ResourceManager;
 import org.junit.jupiter.api.Test;
 import org.lwjgl.opengl.GL11;
 import org.lwjgl.opengl.GL13;
@@ -67,4 +69,36 @@ class SamplerBindGenerationTest {
 
         assertEquals(55, st.boundTextures[2], "unit 2 keeps its binding after the active unit moves away");
     }
+
+    @Test
+    void settingAnUnchangedTexParameterOnAResolvedSamplerDoesNotBumpTheGeneration() {
+        final SDLGPURenderBackend backend = new SDLGPURenderBackend();
+        final ContextState st = SdlTestRig.contextState();
+        final ResourceManager resourceManager = Reflect.get(backend, "resourceManager");
+
+        backend.activeTexture(GL13.GL_TEXTURE0);
+        backend.bindTexture(GL11.GL_TEXTURE_2D, 42);
+        backend.texParameteri(GL11.GL_TEXTURE_2D, GL11.GL_TEXTURE_MIN_FILTER, GL11.GL_LINEAR);
+        resourceManager.getTexSamplerState(42).sdlSampler = 1L;
+        final int before = st.samplerBindGen;
+
+        backend.texParameteri(GL11.GL_TEXTURE_2D, GL11.GL_TEXTURE_MIN_FILTER, GL11.GL_LINEAR);
+        assertEquals(before, st.samplerBindGen);
+
+        backend.texParameteri(GL11.GL_TEXTURE_2D, GL11.GL_TEXTURE_MIN_FILTER, GL11.GL_NEAREST);
+        assertNotEquals(before, st.samplerBindGen);
+    }
+
+    @Test
+    void theFirstTexParameterOnAStatelessTextureBumpsEvenAtTheDefaultValue() {
+        final SDLGPURenderBackend backend = new SDLGPURenderBackend();
+        final ContextState st = SdlTestRig.contextState();
+
+        backend.activeTexture(GL13.GL_TEXTURE0);
+        backend.bindTexture(GL11.GL_TEXTURE_2D, 43);
+        final int before = st.samplerBindGen;
+
+        backend.texParameteri(GL11.GL_TEXTURE_2D, GL11.GL_TEXTURE_MIN_FILTER, GL11.GL_NEAREST_MIPMAP_LINEAR);
+        assertNotEquals(before, st.samplerBindGen, "creating the sampler state replaces the default sampler");
+    }
 }
diff --git a/src/main/java/com/gtnewhorizons/angelica/debug/flyby/FlybyRunner.java b/src/main/java/com/gtnewhorizons/angelica/debug/flyby/FlybyRunner.java
index 620702d87..97bf79ddf 100644
--- a/src/main/java/com/gtnewhorizons/angelica/debug/flyby/FlybyRunner.java
+++ b/src/main/java/com/gtnewhorizons/angelica/debug/flyby/FlybyRunner.java
@@ -8,9 +8,12 @@ import com.gtnewhorizons.angelica.debug.profiling.AsprofRecorder.StopStatus;
 import com.gtnewhorizons.angelica.glsm.GLStateManager;
 import com.gtnewhorizons.angelica.glsm.backend.VSyncMode;
 import com.gtnewhorizons.angelica.glsm.profiling.Tracy;
+import com.gtnewhorizons.angelica.glsm.profiling.DebugCounters;
 import com.gtnewhorizons.angelica.rendering.FpsReducer;
 import com.gtnewhorizons.angelica.rendering.FramePacer;
 import com.gtnewhorizons.angelica.rendering.IsbrhTestRenderer;
+import com.sun.management.OperatingSystemMXBean;
+import com.sun.management.ThreadMXBean;
 import cpw.mods.fml.common.eventhandler.SubscribeEvent;
 import cpw.mods.fml.common.gameevent.TickEvent;
 import net.minecraft.client.Minecraft;
@@ -33,6 +36,8 @@ import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.lwjgl.opengl.Display;
 
+import java.lang.management.GarbageCollectorMXBean;
+import java.lang.management.ManagementFactory;
 import java.util.Arrays;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.atomic.AtomicReference;
@@ -110,11 +115,23 @@ public final class FlybyRunner {
     private long legSection;
 
     private long[] frameTimesNs = NO_FRAMES;
+    private long[] frameAllocBytes = NO_FRAMES;
+    private long lastAllocBytes;
+    private long gcCountStart;
+    private long gcTimeStart;
+    private long cpuClientStartNs;
+    private long cpuProcessStartNs;
+    private long fenceWaitStartNs;
+    private long transferWaitStartNs;
+    private long presentsStart;
+    private long emptyAcquiresStart;
+    private long allocClientStart;
+    private long allocProcessStart;
     private int frameCount;
     private final int[] phaseStartFrame = new int[64];
     private final int[] phaseKey = new int[64];
     private int phaseCount;
-    private boolean framesTruncated;
+    private int framesSeen;
     private long lastFrameNs;
     private long runStartNs;
 
@@ -174,7 +191,7 @@ public final class FlybyRunner {
         this.warmupTicks = Math.max(0, warmupTicks);
         this.tick = 0;
         this.frameCount = 0;
-        this.framesTruncated = false;
+        this.framesSeen = 0;
         this.waitForTracy = false;
         this.waitForFocus = false;
         this.exitWhenDone = false;
@@ -292,14 +309,16 @@ public final class FlybyRunner {
         if (event.phase != TickEvent.Phase.END || this.state != State.RUNNING) return;
 
         final long now = System.nanoTime();
+        final long alloc = AllocBean.allocatedBytes();
         if (this.lastFrameNs != 0L) {
             if (this.frameCount < this.frameTimesNs.length) {
+                this.frameAllocBytes[this.frameCount] = alloc >= 0L && this.lastAllocBytes >= 0L ? alloc - this.lastAllocBytes : -1L;
                 this.frameTimesNs[this.frameCount++] = now - this.lastFrameNs;
-            } else {
-                this.framesTruncated = true;
             }
+            this.framesSeen++;
         }
         this.lastFrameNs = now;
+        this.lastAllocBytes = alloc;
 
         if (this.shot < SystemProperties.FLYBY_SCREENSHOTS && this.tick >= this.nextShot) {
             final Minecraft mc = Minecraft.getMinecraft();
@@ -493,8 +512,21 @@ public final class FlybyRunner {
         this.plotLeg = Tracy.plotHandle("flyby.leg");
         this.plotTurning = Tracy.plotHandle("flyby.turning");
         this.lastPhase = -1;
-        this.frameTimesNs = new long[Math.min(MAX_RECORDED_FRAMES, Math.max(1024, this.runTicks * 20))];
+        this.frameTimesNs = new long[Math.min(MAX_RECORDED_FRAMES, Math.max(1024, this.runTicks * 50))];
+        this.frameAllocBytes = new long[this.frameTimesNs.length];
+        this.lastAllocBytes = -1L;
+        this.gcCountStart = gcCount();
+        this.gcTimeStart = gcTimeMs();
+        this.cpuClientStartNs = clientCpuNs();
+        this.cpuProcessStartNs = processCpuNs();
+        this.fenceWaitStartNs = DebugCounters.FENCE_WAIT_NANOS.sum();
+        this.transferWaitStartNs = DebugCounters.TRANSFER_WAIT_NANOS.sum();
+        this.presentsStart = DebugCounters.PRESENTS.sum();
+        this.emptyAcquiresStart = DebugCounters.EMPTY_ACQUIRES.sum();
+        this.allocClientStart = AllocBean.allocatedBytes();
+        this.allocProcessStart = AllocBean.totalAllocatedBytes();
         this.frameCount = 0;
+        this.framesSeen = 0;
         this.phaseCount = 0;
         this.lastFrameNs = 0L;
         this.runStartNs = System.nanoTime();
@@ -720,7 +752,7 @@ public final class FlybyRunner {
         this.legSection = 0L;
         Tracy.sectionLeave(this.runSection);
         this.runSection = 0L;
-        if (Tracy.ENABLED) Tracy.message("flyby end route=" + this.route.id() + " frames=" + this.frameCount);
+        if (Tracy.ENABLED) Tracy.message("flyby end route=" + this.route.id() + " frames=" + this.framesSeen);
 
         final String summary = this.summarise(elapsedNs, player);
         LOGGER.info(summary);
@@ -800,13 +832,28 @@ public final class FlybyRunner {
     }
 
     private String summarise(long elapsedNs, EntityClientPlayerMP player) {
+        final long allocClientEnd = AllocBean.allocatedBytes();
+        final long allocProcessEnd = AllocBean.totalAllocatedBytes();
         final StringBuilder sb = new StringBuilder(192);
         sb.append("Flyby ").append(this.route.id())
-          .append(": ").append(this.frameCount).append(" frames in ")
+          .append(": ").append(this.framesSeen).append(" frames in ")
           .append(String.format("%.2fs", elapsedNs / 1_000_000_000.0D));
 
-        if (this.frameCount > 0) appendFrameStats(sb, 0, this.frameCount);
-        if (this.framesTruncated) sb.append(" (frame samples truncated)");
+        if (this.frameCount > 0) {
+            appendFrameStats(sb, 0, this.frameCount);
+            appendAllocStats(sb, allocClientEnd, allocProcessEnd);
+        }
+        sb.append(", gc ").append(gcCount() - this.gcCountStart).append(" collections ").append(gcTimeMs() - this.gcTimeStart).append("ms");
+        appendCpuStats(sb);
+        if (this.framesSeen > 0) {
+            sb.append(String.format(", wait fence %.4fms/frame, transfer %.4fms/frame",
+                (DebugCounters.FENCE_WAIT_NANOS.sum() - this.fenceWaitStartNs) / (double) this.framesSeen / 1e6D,
+                (DebugCounters.TRANSFER_WAIT_NANOS.sum() - this.transferWaitStartNs) / (double) this.framesSeen / 1e6D));
+            sb.append(String.format(", presents %d, empty acquires %d",
+                DebugCounters.PRESENTS.sum() - this.presentsStart,
+                DebugCounters.EMPTY_ACQUIRES.sum() - this.emptyAcquiresStart));
+        }
+        if (this.framesSeen > this.frameCount) sb.append(" (frame samples truncated)");
         for (int i = 0; i < this.phaseCount; i++) {
             final int from = this.phaseStartFrame[i];
             final int to = i + 1 < this.phaseCount ? this.phaseStartFrame[i + 1] : this.frameCount;
@@ -832,6 +879,82 @@ public final class FlybyRunner {
             sorted[n - 1] / 1e6D));
     }
 
+    private void appendAllocStats(StringBuilder sb, long clientEnd, long processEnd) {
+        if (this.allocClientStart < 0L || clientEnd < 0L) {
+            sb.append(", alloc unavailable");
+            return;
+        }
+        final long total = clientEnd - this.allocClientStart;
+        sb.append(String.format(", alloc client avg %.0fB/frame, total %.1fMB", total / (double) this.framesSeen, total / 1048576.0D));
+        final long[] sorted = Arrays.copyOf(this.frameAllocBytes, this.frameCount);
+        Arrays.sort(sorted);
+        int first = 0;
+        while (first < sorted.length && sorted[first] < 0L) first++;
+        final int n = sorted.length - first;
+        if (n > 0) sb.append(String.format(", p50 %dB, p99 %dB", sorted[first + n / 2], sorted[first + Math.min(n - 1, (int) (n * 0.99D))]));
+        if (this.allocProcessStart >= 0L && processEnd >= 0L) {
+            sb.append(String.format(", alloc process %.0fB/frame", (processEnd - this.allocProcessStart) / (double) this.framesSeen));
+        }
+    }
+
+    private void appendCpuStats(StringBuilder sb) {
+        final long client = clientCpuNs();
+        final long process = processCpuNs();
+        if (this.framesSeen == 0 || this.cpuClientStartNs < 0L || this.cpuProcessStartNs < 0L || client < 0L || process < 0L) {
+            sb.append(", cpu unavailable");
+            return;
+        }
+        sb.append(String.format(", cpu client %.3fms/frame, process %.3fms/frame",
+            (client - this.cpuClientStartNs) / (double) this.framesSeen / 1e6D,
+            (process - this.cpuProcessStartNs) / (double) this.framesSeen / 1e6D));
+    }
+
+    private static long clientCpuNs() {
+        final var bean = ManagementFactory.getThreadMXBean();
+        return bean.isCurrentThreadCpuTimeSupported() ? bean.getCurrentThreadCpuTime() : -1L;
+    }
+
+    private static long processCpuNs() {
+        return ManagementFactory.getOperatingSystemMXBean() instanceof OperatingSystemMXBean os ? os.getProcessCpuTime() : -1L;
+    }
+
+    private static long gcCount() {
+        long total = 0L;
+        for (GarbageCollectorMXBean gc : ManagementFactory.getGarbageCollectorMXBeans()) total += Math.max(0L, gc.getCollectionCount());
+        return total;
+    }
+
+    private static long gcTimeMs() {
+        long total = 0L;
+        for (GarbageCollectorMXBean gc : ManagementFactory.getGarbageCollectorMXBeans()) total += Math.max(0L, gc.getCollectionTime());
+        return total;
+    }
+
+    private static final class AllocBean {
+        static final ThreadMXBean BEAN;
+        static final boolean TOTAL;
+        static {
+            ThreadMXBean bean = null;
+            boolean total = false;
+            try {
+                if (ManagementFactory.getThreadMXBean() instanceof ThreadMXBean sun && sun.isThreadAllocatedMemorySupported()) {
+                    bean = sun;
+                    total = sun.getTotalThreadAllocatedBytes() >= 0L;
+                }
+            } catch (Throwable ignored) {}
+            BEAN = bean;
+            TOTAL = total;
+        }
+
+        static long allocatedBytes() {
+            return BEAN == null ? -1L : BEAN.getCurrentThreadAllocatedBytes();
+        }
+
+        static long totalAllocatedBytes() {
+            return TOTAL ? BEAN.getTotalThreadAllocatedBytes() : -1L;
+        }
+    }
+
     public void cancel() {
         if (this.isActive()) {
             LOGGER.info("Flyby cancelled");