Ah, I've made a mistake, my build is 7057, that's the latest one. My specs:
Intel Pentium 4 3,6 Ghz
2 GB DDR2 RAM
Sapphire ATI readeon X1800 512 Mb
Creative Sound Blaster Audigy 4; A shame, but I don't remember what motherboard I have.
Fullscreen-mode seems to help a bit, maybe gives 1-2 fps. The drivers for graphics card are up to date. If it works fine for you, then I guess it's something special in my build.