No reason, no reason at all zapretila game (Styx: Shards of Darkness)

Passed a great part of the game, lag, freezes were not, reached the 7th mission began. The game became hard to freesite literally jerks goes, resetting the increased fps but the freezes remained. Restarting the computer few minutes it normalizes the situation, but then starts again. On the rise, with light freezes to the slide show. In other games this is not observed, consequently it is not in the computer, and the game itself. What to do? I would understand this to be the beginning of the game, but everything was normal, what could happen?! The delusion of some kind.