umm, i sense it's a video ram deficit problem. Do you use a laptop or onboard videocard? Your video memory buffer isn't big enuff to display the game's textures so it has to swap/share with the much slower system memory. Like Laxation says you need a better vcard or try add more system ram.
Besides updating drivers, try to crank up the AGP-Aperture in BIOS and lower down the AGP-Speed from 8x to 4x.
If that doesn't cut it, then you absolutely need a better video card with more ram.
