diff --git a/src/webgpu/api/operation/command_buffer/queries/timestampQuery.spec.ts b/src/webgpu/api/operation/command_buffer/queries/timestampQuery.spec.ts
index 7ac90ec7a007..9e83f8044c88 100644
--- a/src/webgpu/api/operation/command_buffer/queries/timestampQuery.spec.ts
+++ b/src/webgpu/api/operation/command_buffer/queries/timestampQuery.spec.ts
@@ -40,6 +40,11 @@ and prevent pages from running.
 
     t.skipIfDeviceDoesNotHaveFeature('timestamp-query');
 
+    if (numQuerySets === 65536) {
+      // Allow extra time for massive timestamp query allocation/cleanup churn.
+      t.setEndTestScopeTimeout(10000);
+    }
+
     const view = t
       .createTextureTracked({
         size: [1, 1, 1],
diff --git a/src/webgpu/gpu_test.ts b/src/webgpu/gpu_test.ts
index 9335592d4849..24b047267695 100644
--- a/src/webgpu/gpu_test.ts
+++ b/src/webgpu/gpu_test.ts
@@ -1460,6 +1460,12 @@ export class GPUTest extends GPUTestBase {
     assert(this.provider !== undefined, 'internal error: GPUDevice missing?');
     this.provider.expectDeviceLost(reason);
   }
+
+  /** Adjust timeout used when releasing the device after a test finishes. */
+  setEndTestScopeTimeout(timeoutMs: number): void {
+    assert(this.provider !== undefined, 'internal error: GPUDevice missing?');
+    this.provider.setEndTestScopeTimeout(timeoutMs);
+  }
 }
 
 /**
diff --git a/src/webgpu/util/device_pool.ts b/src/webgpu/util/device_pool.ts
index ba3135777998..5055c3577edb 100644
--- a/src/webgpu/util/device_pool.ts
+++ b/src/webgpu/util/device_pool.ts
@@ -14,11 +14,14 @@ import { getDefaultLimits, kPossibleLimits } from '../capability_info.js';
 // MUST_NOT_BE_IMPORTED_BY_DATA_CACHE
 // This file should not be transitively imported by .cache.ts files
 
+const kDefaultEndTestScopeTimeoutMs = 5000;
+
 export interface DeviceProvider {
   /** Adapter the device was created from. Cannot be reused; just for adapter info. */
   readonly adapter: GPUAdapter;
   readonly device: GPUDevice;
   expectDeviceLost(reason: GPUDeviceLostReason): void;
+  setEndTestScopeTimeout(timeoutMs: number): void;
 }
 
 class TestFailedButDeviceReusable extends Error {}
@@ -351,6 +354,7 @@ class DeviceHolder implements DeviceProvider {
   expectedLostReason?: GPUDeviceLostReason;
   /** Number of test cases the device has been used for. */
   testCaseUseCounter = 0;
+  private endTestScopeTimeoutMs = kDefaultEndTestScopeTimeoutMs;
 
   // Gets a device and creates a DeviceHolder.
   // If the device is lost, DeviceHolder.lost gets set.
@@ -395,6 +399,7 @@ class DeviceHolder implements DeviceProvider {
     this.device.pushErrorScope('validation');
     this.device.pushErrorScope('internal');
     this.device.pushErrorScope('out-of-memory');
+    this.endTestScopeTimeoutMs = kDefaultEndTestScopeTimeoutMs;
   }
 
   /** Mark the DeviceHolder as expecting a device loss when the test scope ends. */
@@ -403,21 +408,29 @@ class DeviceHolder implements DeviceProvider {
     this.expectedLostReason = reason;
   }
 
+  setEndTestScopeTimeout(timeoutMs: number): void {
+    assert(this.state === 'acquired');
+    assert(timeoutMs >= 0, 'timeout must be non-negative');
+    this.endTestScopeTimeoutMs = timeoutMs;
+  }
+
   /**
    * Attempt to end test scopes: Check that there are no extra error scopes, and that no
    * otherwise-uncaptured errors occurred during the test. Time out if it takes too long.
    */
   endTestScope(): Promise<void> {
     assert(this.state === 'acquired');
-    const kTimeout = 5000;
-
     // Time out if attemptEndTestScope (popErrorScope or onSubmittedWorkDone) never completes. If
     // this rejects, the device won't be reused, so it's OK that popErrorScope calls may not have
     // finished.
     //
     // This could happen due to a browser bug - e.g.,
     // as of this writing, on Chrome GPU process crash, popErrorScope just hangs.
-    return raceWithRejectOnTimeout(this.attemptEndTestScope(), kTimeout, 'endTestScope timed out');
+    return raceWithRejectOnTimeout(
+      this.attemptEndTestScope(),
+      this.endTestScopeTimeoutMs,
+      'endTestScope timed out'
+    );
   }
 
   private async attemptEndTestScope(): Promise<void> {