src/java.desktop/windows/classes/sun/awt/windows/WDesktopProperties.java

*** 239,259 ****
       * Called by WToolkit when Windows settings change-- we (re)load properties and
       * set new values.
       */
      @SuppressWarnings("unchecked")
      synchronized Map<String, Object> getProperties() {
!         ThemeReader.flush();
  
          // load the changed properties into a new hashmap
          map = new HashMap<String, Object>();
          getWindowsParameters();
          map.put(SunToolkit.DESKTOPFONTHINTS, SunToolkit.getDesktopFontHints());
          map.put(PROP_NAMES, getKeyNames());
          // DnD uses one value for x and y drag diff, but Windows provides
          // separate ones.  For now, just use the x value - rnk
          map.put("DnD.Autoscroll.cursorHysteresis", map.get("win.drag.x"));
  
          return (Map<String, Object>) map.clone();
      }
  
      /*
       * This returns the value for the desktop property "awt.font.desktophints"
--- 239,270 ----
       * Called by WToolkit when Windows settings change-- we (re)load properties and
       * set new values.
       */
      @SuppressWarnings("unchecked")
      synchronized Map<String, Object> getProperties() {
!         Map<String, Object> prev = map==null?null:new HashMap<>(map);
          
          // load the changed properties into a new hashmap
          map = new HashMap<String, Object>();
          getWindowsParameters();
          map.put(SunToolkit.DESKTOPFONTHINTS, SunToolkit.getDesktopFontHints());
          map.put(PROP_NAMES, getKeyNames());
          // DnD uses one value for x and y drag diff, but Windows provides
          // separate ones.  For now, just use the x value - rnk
          map.put("DnD.Autoscroll.cursorHysteresis", map.get("win.drag.x"));
  
+         // if ThemeReader.flush() always called on windowSettingChange, 
+         // for some reason many windowSettingChange event would be generated on
+         // window resize, and it would decrease rendering performance while 
+         // resizing a window. so only flush the ThemeReader if there are changed
+         // properties. 
+         if(prev == null || 
+                 !prev.keySet().equals(map.keySet()) ||
+                 !Arrays.deepEquals(prev.values().toArray(), map.values().toArray())) {
+             ThemeReader.flush();
+         }
+         
          return (Map<String, Object>) map.clone();
      }
  
      /*
       * This returns the value for the desktop property "awt.font.desktophints"