Well it depends on your system and graphics card. Did you do a full install? This helps speed up the game. I have a pretty good machine (Athalon 900mhz, 64 meg RAM, etc....) but the game runs slowly for me sometimes too.
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Never try to teach a pig to sing; it wastes your time and it annoys the pig
I've got to admit it's getting better, it's getting better all the time