The claim is that the transparency in Aero does not affect performance. But if you're the suspicious sort, or you just don't go in for that sort of thing, you can disable it pretty easily. Just right click the mouse on the desktop and select the "Personalize" option. In the window that gets opened, select the "Window Color and Appearance" which should be near the top. In the new window that opens, uncheck the "Enable transparency" then click OK. You are done, Aero transparency is disabled.