Meows optimalization files a little bit solved this problem for me - but not completely. I guess its something with the new textures/maps.
But final solution was to buy another PC, now i can run everything on maxed out settings. But before i didn't have a bad PC either, I had i7 2GHz, 8GB ram, NVIDIA GeForce GT 525M 1GB ram.
And I remember absolutely clearly, that with this PC i was able to run cRPG on maxed out settings smoothly as well a few months ago.