I dunno if it will help but on my system I have the sim running fairly nice at 20 fps (except when over cities like L. A. Then it drops about an average of 5 fps). Even have the autogen up at the second position. I had to sacrifice water effects and have it at the lowest setting, but then I have auto trafic at 50%, commercial ai at 50%, GA traffic at 25%, airport vehicles at 50%, boats and ships at 10%.

I've done most of the tweeks and have this:

Del Dim 9100 Pent D 820
it's only a 2.8 Gig
3.5 GBs of pc4200 Ram
nVidia 6800 ultra 256

I'm guessing it's all the ram helping to run it better being a relatively slow processor. But ram is a pretty cheap upgrade over buying  5 or $600 super video card.

Keni