my system's pretty new:
i7 930
3gb ram
9800gtx+
i'm using mostly medium range settings, with the fancy stuff(aa/anistrophic, etc) turned off. the game runs smoothly for the most part(70+ fps), however, it seems whenever there are battles involving cannons, the game slows to a crawl. also, cities lag. a lot.
i've learned that turning scene and drawing distance down will make the buildings pop up at a shorter distance, but cities still fare pretty badly in terms of fps.
i have set an experiment where i used the editor to create 2 scenarios. one involving lots of gunpods, cannons, etc, and the other missile oriented. the difference is about 40fps, which is astonishing...sometimes it'll even drop to single digits when ships starts spewing shells at eachother.
i think the ballistic calculation, with so many cannon rounds flying everywhere is costing performance. also, do they have to render the shadow on every single bullet? i think the ka 50's cannon uses no shadow, and it runs much better. maybe it's the shadow's fault.