Create function updatePhysicalSize.

Runtime/editor/editor_window.cs

 
         protected float deltaTime;
         protected float unscaledDeltaTime;
+        
+        void updatePhysicalSize() {
+            var size = this.queryWindowSize();
+            this._lastWindowWidth = size.x;
+            this._lastWindowHeight = size.y;
+            this._physicalSize = new Size(
+                this._lastWindowWidth * this._devicePixelRatio,
+                this._lastWindowHeight * this._devicePixelRatio);
+        }
+
 
         protected virtual void updateDeltaTime() {
             this.deltaTime = Time.unscaledDeltaTime;
         public void onViewMetricsChanged() {
             this._viewMetricsChanged = true;
         }
-
+        
-            var size = this.queryWindowSize();
-            this._lastWindowWidth = size.x;
-            this._lastWindowHeight = size.y;
-            this._physicalSize = new Size(
-                this._lastWindowWidth * this._devicePixelRatio,
-                this._lastWindowHeight * this._devicePixelRatio);
-
+            this.updatePhysicalSize();
             this.updateSafeArea();
             D.assert(this._surface == null);
             this._surface = this.createSurface();
 
         public void Update() {
             if (this._physicalSize == null || this._physicalSize.isEmpty) {
-                var size = this.queryWindowSize();
-                this._lastWindowWidth = size.x;
-                this._lastWindowHeight = size.y;
-                this._physicalSize = new Size(
-                    this._lastWindowWidth * this._devicePixelRatio,
-                    this._lastWindowHeight * this._devicePixelRatio);
+                this.updatePhysicalSize();
             }
 
             this.updateDeltaTime();

Runtime/engine/UIWidgetsPanel.cs

 
         protected override Vector2 queryWindowSize() {
             var rect = this._uiWidgetsPanel.rectTransform.rect;
+            // Here we use ReferenceEquals instead of "==" due to
+            // https://blogs.unity3d.com/2014/05/16/custom-operator-should-we-keep-it/
+            // In short, "==" is overloaded for UnityEngine.Object and will bring performance issues
             if (!ReferenceEquals(this._uiWidgetsPanel.canvas, null)) {
                 var size = new Vector2(rect.width, rect.height) *
                            this._uiWidgetsPanel.canvas.scaleFactor / this._uiWidgetsPanel.devicePixelRatio;