Unless you need it for compatibility to get the game to run, everyone should drop the -winxp and memory tags on startup. Keeping it on negates most of the performance increases from the 1.07 patch. With it off I'm getting a 15-25% fps improvement on a very complicated Dom server (all settings maxed and view at 5km) from 25-30 fps average to 30-40 fps average. Same story for the campaign missions.
FYI my machine is a i7 920 oc'd to 4ghz with HT turned off, 6gb of ram at 1800, and 2x 5850