Slow graphics in Linux (Ubuntu 18.04.1 LTS, GNOME 3.28.2)?

Recently put Linux Mint on a new laptop. Noticed that everything on the screen slows down about every 5-10 seconds. To be could not. The system is fast. I remembered that when you install systems with me when I pointed out that I want to install Proprietary & ThirdParty drivers, worked some kind of Secure Boot and there it was necessary to change/set a password. I just remembered that I made it all wrong and installed it as it happened. The system it established.

So tonight I started the video and I noticed that the system regularly podlagivaet. I pulled the Windows, hold the button and watched as the symbols appear in a text editor. In General, it was obvious that constantly .. regardless of the task. I reinstalled the system. Carefully followed instructions for setting up SecureBoot and everything started to work perfectly.

I'm almost surethat the problem was this.