Hubert! Hard to tell since that map is very small and you cant move around, but for what I can make of it, that map doesnt suffer from that issue!
wlape3! Have Win7 Ultimate 64bit and i7-2600k, 2x HD6950 2gb and 8gb memory and I think that would be sufficent. Also already tried what you wrote and alot more but nothing made any difference, will try the game on my laptop just to see if the same happens!