performanceoverlay

Runtime/editor/editor_window.cs

             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();
         }
 

Samples/UIWidgetsGallery/gallery/app.cs

                 theme: GalleryTheme.kLightGalleryTheme,
                 textScaleFactor: GalleryTextScaleValue.kAllGalleryTextScaleValues[0],
                 timeDilation: SchedulerBinding.instance.timeDilation,
-                platform: Application.platform
+                platform: Application.platform,
+                showPerformanceOverlay: this.widget.enablePerformanceOverlay
             );
         }