it's useless stay here to find a problem on our side...the problem it's just the game engine.
i have the same problem and stop playing for this...
it's clear the problem it's only on some/too much machine since a lot doesen't have any problem
with my pc spec i can play all recent game with decent quality...and i can't play a 2009 game...
i do not want play 1900X1900 i just want play 1024 resolution... i have 20/30 fps around the map and 3 fps in the city...so until they don't do something it's frustrating playing on this condition
cpu athlon x2 3.8ghz
4gb ddr2 800
ati hd 6670
win 7 x64