A red square around the cursor.

A red square around the cursor appears when you click on the icons in the dock.

I can move the clamped cursor to repeat the effect. This happens only with the dock. And under random circumstances. The computer is working properly.

The video card is in order. In Windows including everything works properly and without bugs. I believe this is a bug in MacOS Sierra.

Even in the mode of working on the Intel card, even the interface for opening a folder from the dock is slow.

Apple is disappointing.

Video:

https://drive.google.com/file/d/0B4GjFYqQrpKgdk9NeXpqNkh3NTQ/view?usp=sharing