Ground Combat Choppy, and long AI turns. Fixable?

I've have massive space battles with hundreds of ships and the game runs fine. But ground combat is *extremely* choppy. Taking a planet is really clumsy as it is, this makes me want to just cleanse it from orbit to avoid the hassle, but that goes against the way I want to play. So, any advice on fixing this issue?

I have a P4 3.00ghz with Hyperthreading, 2gb RAM, SB Audigy Gamer, and an nvidia GeForce 6800GT. My system is clean of the usual BS and is tweaked as much as I can get it. Defragged Hard Drive, no heat issues, all drivers updated and the game is patched to 1.63.

Also, some 100 turns into the game even on smaller galaxies with less AIs, their turns start to take quite a long time. I have to do a lot more with so many ships and such to manage, so my turns take long enough but the addition of the AI's time makes the game slow to a tedious crawl. Also, if I enable ministers the Processing after all players is tripled in duration and the music loops every 6 seconds or so during.

I find the minimum specs for this game puzzling. My computer while not that great, absolutely destroys the min specs for the game.