Some graphics cards and drivers play Dom2 very slowly, unless you crank down the detail settings. Updating or changing drivers may also help.
Note too that if you have a center mouse button (or mouse wheel that can be used as one, which many people don't realize), then you can use that to scroll the map, rather than the keyboard arrows.
I had the same problem with the Demo, which I thought was weird, considering I have a 1.7gh processor and a 24 meg video card. But when I thought about it a bit I said "AHHH, nVidia!" and downloaded the newest drivers. Voila! Fast, lovely godhood!
There ARE patches out - try patching to 2.08. But as mentioned, the problem is most likely driver-related, so determine your video card chip maker and download the latest drivers from their site, probably www.ati.com or www.nvidia.com.