its weird because it only seems to effect some people, with my system, i only get a quick stutter right as the game starts, and then its 60fps + all the way, this happens both in single and multiplayer games.
It wouldn't suprise me if it's related to the 512mb of vram. You might just lower a setting to make it playable.
From my experience with the new 10.7 beta drivers that enable AA support in SC2 on 5870's: I found that I can max everything and turn AA to x4 and it runs smooth as silk. As soon as I tried x8 AA, it ran unbelievably bad.
To make that large of a difference, I'm guessing it ran out of v-ram, but I can't find benchmarks to proove this, so it's just a suspecision for now.
The reason it may have worked great in MP and not in SP could be related to map sizes. If they keep the whole map loaded in v-ram, the map size would make a large impact on performance if your v-ram is low.
I think the game is somewhat more demanding them people put it as, i play 1920 x 1080 on ultra with a pretty heavily overclocked 460 and it sometimes dips into the 50's with alot of units on the screen, I'm using ultra textures, but i'd say it's surpising demanding
xaero1ne well no duh your staying over 60fps with a 700 dollar card, with 4 times the shaders cores of mortesv