Unity 5.2 Canvas.RenderOverlays serious fps hit

Hello. To fade in/out (cinematographic effect, when the screen smoothly turns black) the screen I use Canvas with black image on it, and smoothly lerp CanvasGroup Alpha value over time.
Updated Unity to 5.2 just now and this system turned into a massive performance hit.

As you may see, that purple spikes represent FadeIn and FadeOut. Game plays like in slide-show during this translations.
I had read over Upgrade Guide but foud nothing helpful…

Okay, I still don’t know how to deal with huge images dynamic transparency (which is causing the hit) but in my case just had replaced UI.Image with Sprite and all went fine

Edit:
Fixed in 5.3.6:

I’ve the same problem here…