to be honest ive never noticed anything less then perfect... if i cant see a line or something, i usually forgot that i had it turned off haha. i have a few times had like a 250+ part assembly (2/3 of that prolly being sub assemblies) open and if i try to rotate it fast it stutters for about a half a second at frist, but then its fine the rest of the session. Once in a great while a few surfaces wont show up, but if i set the curve smoothness like around 100 or so it fixes it. i actually took the design acccelerator button off my toolbar.. never needed it. and this is all the while running itunes, excel, i explorer, and which other reference materials, if not another window of alibre itself. just keep ur drivers updated, and keep the computer box cool and you'll be aces