Strange intermittent freezes (STALKER: Call of Pripyat)

During the game there are freezes - the game gets up for a few seconds, especially when saving and when you exit / enter the menu, when you just run, freezes are rare, but guaranteed in the cases described earlier. Those. you play - everything is fine, press "quick save" - ​​freeze. And yet, when I installed and launched it, how to describe it, a certain flickering of the screen started, half the screen is black, half the screen with an image, some ripples started, I eliminated it, I don't remember how. The game pulls at maximum speed. The most funny thing is that a few months ago I put the game and went through several times without the slightest freeze and bug, and now such chaos is happening in the game ... Firewood, direct - everything new is installed. What is the problem?