i have exactly the same problem and no one seemed to be able to help me out.
i tried updating my graphics drivers and that made the game speed up but all the textures went weird and messed up.
i suggest you try the same thing and hope that you get better results than i did.
also: it didn't work for me but... have you installed the latest patch?
if not, it's available
here
EDIT: also... welcome to hell
:thumbup: