Unity 5.2 Canvas.RenderOverlays serious fps hit

Here is the script that i use to change the alpha of a canvasgroup:

     private IEnumerator GoInCanvasEffect(CanvasGroup _canvasgroup, float _alphaSpeedFactor = 1f, bool _interactable = true, Selectable _nextButton = null)
     {
         #region GO IN CANVAS GROUP
         if(_canvasgroup.gameObject == null)
         {
             return true;
         }
 //        Debug.Log("Put on Screen: " + _canvasgroup.name);
         _canvasgroup.gameObject.SetActive(true);
         
         float alpha = _canvasgroup.alpha;
         float lerpFactor = 0;
         while(_canvasgroup.alpha < 1)
         {
             lerpFactor += _alphaSpeedFactor * Time.unscaledDeltaTime;
             _canvasgroup.alpha = Mathf.Lerp(alpha , 1.0f, lerpFactor);
             yield return new WaitForEndOfFrame();
             if(_canvasgroup.alpha >= 0.99f) _canvasgroup.alpha = 1.0f;
         }
 
         yield return StartCoroutine(CoroutineUtil.WaitForRealSeconds(0.1f));
 //        yield return new WaitForSeconds(0.1F);
         _canvasgroup.blocksRaycasts = _interactable;
         _canvasgroup.interactable = _interactable;

         }
         #endregion
     }

Do you have any luck to fix this? I'm still use the old Unity version, because this bug still there since 5.2

We are seeing the same issue too, but in our case on a Text object in the UI, so replacing with UIImage is not an option in our case. Only happened when we moved up to Unity 5.2.x

Has anyone tried it with one of the patched versions of Unity? 5.2.1p1 does mention a fix to some UI performance regressions, but not clear if it's the same issue.

I also observe that if you switch the profiler to the timeline view, it is waiting on a canvas sort job during the spike.