partly reverted previous fix: update only gutter size on layout to avoid scrolling slow down, but still fix blinking

platform/platform-impl/src/com/intellij/openapi/editor/impl/EditorGutterComponentImpl.java

@@ -544,8 +544,12 @@ class EditorGutterComponentImpl extends EditorGutterComponentEx implements Mouse
   }
 
   public void updateSize() {
+    updateSize(false);
+  }
+
+  void updateSize(boolean onLayout) {
     int prevHash = sizeHash();
-    updateSizeInner();
+    updateSizeInner(onLayout);
 
     if (prevHash != sizeHash()) {
       fireResized();
@@ -553,9 +557,11 @@ class EditorGutterComponentImpl extends EditorGutterComponentEx implements Mouse
     repaint();
   }
 
-  private void updateSizeInner() {
-    calcIconAreaWidth();
-    calcAnnotationsSize();
+  private void updateSizeInner(boolean onLayout) {
+    if (!onLayout) {
+      calcIconAreaWidth();
+      calcAnnotationsSize();
+    }
     calcAnnotationExtraSize();
   }
 

platform/platform-impl/src/com/intellij/openapi/editor/impl/EditorImpl.java

@@ -959,7 +959,6 @@ public final class EditorImpl extends UserDataHolderBase implements EditorEx, Hi
       public void componentResized(@NotNull ComponentEvent e) {
         myMarkupModel.recalcEditorDimensions();
         myMarkupModel.repaint(-1, -1);
-        myGutterComponent.updateSize();
       }
     });
   }
@@ -6755,6 +6754,16 @@ public final class EditorImpl extends UserDataHolderBase implements EditorEx, Hi
       setupCorners();
     }
 
+    @Override
+    public void layout() {
+      if (isInDistractionFreeMode()) {
+        // re-calc gutter extra size after editor size is set
+        // & layout once again to avoid blinking
+        myGutterComponent.updateSize(true);
+      }
+      super.layout();
+    }
+
     @Override
     protected void processMouseWheelEvent(@NotNull MouseWheelEvent e) {
       if (mySettings.isWheelFontChangeEnabled() && !MouseGestureManager.getInstance().hasTrackpad()) {