fix in UnityEditor performance issue

src/UniTask/Assets/Editor/EditorRunnerChecker.cs

@@ -0,0 +1,28 @@
+#if UNITY_EDITOR
+
+using Cysharp.Threading.Tasks;
+using System;
+using System.IO;
+using System.Linq;
+using UnityEditor;
+using UnityEngine;
+
+public static class EditorRunnerChecker
+{
+    [MenuItem("Tools/UniTaskEditorRunnerChecker")]
+    public static void RunUniTaskAsync()
+    {
+        RunCore().Forget();
+    }
+
+    static async UniTaskVoid RunCore()
+    {
+        Debug.Log("Start, Wait 5 seconds. deltaTime?" + Time.deltaTime);
+
+        await UniTask.Delay(TimeSpan.FromSeconds(5));
+
+        Debug.Log("End, Wait 5 seconds. deltaTime?" + Time.deltaTime);
+    }
+}
+
+#endif

src/UniTask/Assets/Editor/EditorRunnerChecker.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: e51b78c06cb410f42b36e0af9de3b065
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

src/UniTask/Assets/Plugins/UniTask/Runtime/PlayerLoopHelper.cs

@@ -200,6 +200,7 @@ namespace Cysharp.Threading.Tasks
 
 
 #if UNITY_EDITOR
+
         [InitializeOnLoadMethod]
         static void InitOnEditor()
         {
@@ -210,17 +211,34 @@ namespace Cysharp.Threading.Tasks
             EditorApplication.update += ForceEditorPlayerLoopUpdate;
         }
 
+        static double beforeCalledTime;
+
         private static void ForceEditorPlayerLoopUpdate()
         {
-            if (EditorApplication.isPlayingOrWillChangePlaymode || EditorApplication.isCompiling ||
+            if (EditorApplication.isPlayingOrWillChangePlaymode || EditorApplication.isCompiling || EditorApplication.isUpdating)
-                EditorApplication.isUpdating)
             {
                 // Not in Edit mode, don't interfere
                 return;
             }
 
-            //force unity to update PlayerLoop callbacks
+            // EditorApplication.QueuePlayerLoopUpdate causes performance issue, don't call directly.
-            EditorApplication.QueuePlayerLoopUpdate();
+            // EditorApplication.QueuePlayerLoopUpdate();
+
+            if (yielders != null)
+            {
+                foreach (var item in yielders)
+                {
+                    if (item != null) item.Run();
+                }
+            }
+
+            if (runners != null)
+            {
+                foreach (var item in runners)
+                {
+                    if (item != null) item.Run();
+                }
+            }
         }
 
 #endif