I have a 15" uMBP with 4 gigs and every once in a while play a game and my performance is very poor. I'm talking single digit frames on medium and low settings. On cinebench I only get ~2k on the gpu test. When I reset my kernel caches it performs well for about a day then the performance starts to suck again. Nothing else is running and I always have 2+ gigs free on my memory. What could be the problem? I took it to the apple store and it passed all of their tests but that was fairly soon after i reset my kernel cache and it was working properly. ps the game is sims 3 mostly, but also spore.