Why is the game slow? (Cryostasis: Sleep of Reason)

I have a gtx 560, AMD Athlon X4 651 3GHz, 8gb RAM. The game "eats" 250 VRAM 2gb RAM, the percentage is not even half loaded. And at low settings, less than 30 fps, an average of 20-27. The high is the same. How to raise fps?