fix Time. Do not use Stopwatch. Use Time.time.

Runtime/editor/editor_window.cs

 using System;
 using System.Collections.Generic;
-using System.Diagnostics;
 using Unity.UIWidgets.async;
 using Unity.UIWidgets.foundation;
 using Unity.UIWidgets.rendering;
             this._windowAdapter.OnGUI(Event.current);
         }
 
-        float? lastUpdateTime;
-            if (this.lastUpdateTime != null) {
-                float deltaTime = (float)EditorApplication.timeSinceStartup - this.lastUpdateTime.Value;
-                PerformanceUtils.instance.updateDeltaTime(deltaTime);
-            }
-
-            this.lastUpdateTime = (float) EditorApplication.timeSinceStartup;
-            
             this._windowAdapter.Update();
         }
 
         protected override Vector2 queryWindowSize() {
             return this.editorWindow.position.size;
         }
+
+        protected override TimeSpan getTime() {
+            return TimeSpan.FromSeconds(EditorApplication.timeSinceStartup);
+        }
+
+        float? _lastUpdateTime;
+        
+        protected override float getUnscaledDeltaTime() {
+            if (this._lastUpdateTime == null) {
+                this._lastUpdateTime = (float) EditorApplication.timeSinceStartup;
+            }
+
+            float deltaTime = (float) EditorApplication.timeSinceStartup - this._lastUpdateTime.Value;
+            this._lastUpdateTime = (float) EditorApplication.timeSinceStartup;
+            return deltaTime;
+        }        
     }
 
 #endif
         float _lastWindowWidth;
         float _lastWindowHeight;
 
-        readonly TimeSpan _epoch = new TimeSpan(Stopwatch.GetTimestamp());
-
 
         bool _regenerateLayerTree;
         Surface _surface;
             get { return this._alive; }
         }
 
+        protected virtual TimeSpan getTime() {
+            return TimeSpan.FromSeconds(Time.time);
+        }
+
+        protected virtual float getUnscaledDeltaTime() {
+            return Time.unscaledDeltaTime;
+        }
+
         protected virtual void updateSafeArea() {
         }
 
             return new EditorWindowSurface();
         }
 
-
-                this.onBeginFrame(new TimeSpan(Stopwatch.GetTimestamp()) - this._epoch);
+                this.onBeginFrame(this.getTime());
             }
 
             this.flushMicrotasks();
         }
 
         public void Update() {
+            PerformanceUtils.instance.updateDeltaTime(this.getUnscaledDeltaTime());
+            
             Timer.update();
 
             bool hasFocus = this.hasFocus();

Runtime/engine/UIWidgetsPanel.cs

 using Unity.UIWidgets.async;
 using Unity.UIWidgets.editor;
 using Unity.UIWidgets.foundation;
-using Unity.UIWidgets.service;
 using Unity.UIWidgets.ui;
 using Unity.UIWidgets.widgets;
 using UnityEngine;
         }
 
         protected virtual void Update() {
-            PerformanceUtils.instance.updateDeltaTime(Time.unscaledDeltaTime);
             this._displayMetrics.Update();
             UIWidgetsMessageManager.ensureUIWidgetsMessageManagerIfNeeded();