well.... if u customize your desktop with out using any software that takes up you RAm n so on i beleive it wont slow down your system.... if u install konfabulator, avedesk, objecy dock ( other docks ), styler toolbar, y'z shadow, some of the stuff from object desktop n glass 2k will make your system suffer if u have insufficient RAM n ur running high end games.... so... do your deskmods with the consideration of pro's n con's