diff --git a/src/libraries/System.Threading.ThreadPool/tests/ThreadPoolTests.cs b/src/libraries/System.Threading.ThreadPool/tests/ThreadPoolTests.cs
index d61ab0f8968c8c..6895adb2da1f89 100644
--- a/src/libraries/System.Threading.ThreadPool/tests/ThreadPoolTests.cs
+++ b/src/libraries/System.Threading.ThreadPool/tests/ThreadPoolTests.cs
@@ -913,7 +913,7 @@ public static void ThreadPoolThreadCreationDoesNotTransferExecutionContext()
             }).Dispose();
         }
 
-        [ConditionalFact(typeof(ThreadPoolTests), nameof(IsThreadingAndRemoteExecutorSupported))]
+        [ConditionalFact(typeof(ThreadPoolTests), nameof(IsThreadingAndRemoteExecutorSupportedAndNotDebugRuntime))]
         public static void CooperativeBlockingCanCreateThreadsFaster()
         {
             // Run in a separate process to test in a clean thread pool environment such that work items queued by the test
@@ -1501,6 +1501,10 @@ public static unsafe void ThreadPoolCompletedWorkItemCountTest()
         public static bool IsThreadingAndRemoteExecutorSupported =>
             PlatformDetection.IsMultithreadingSupported && RemoteExecutor.IsSupported;
 
+        // Timing-sensitive tests can be too flaky on a Debug runtime, which is much slower
+        public static bool IsThreadingAndRemoteExecutorSupportedAndNotDebugRuntime =>
+            IsThreadingAndRemoteExecutorSupported && !PlatformDetection.IsDebugRuntime;
+
         private static bool GetUseWindowsThreadPool()
         {
             AppContext.TryGetSwitch("System.Threading.ThreadPool.UseWindowsThreadPool", out bool useWindowsThreadPool);