Why unity editor animation preview like this?

Unity Engine
1

I remember before was not like this.

Here is current video.

Animation playing remaining many afterimages.

Very annoying.

Why? How to fix?

Unity newest version(5.6.1f1), nvidia newest driver, working on laptop Asus G752VS

Thanks.

2

Please log a bug.

we had a few regression on the animation previewer because some rendering code did change for directX