There is one program that I use to help improve the game performance before I fire up a game. You could check out
Game Booster. I don't have a high end computer to play a majority of games, but this little program helps a lot by closing down the unneeded processes and open up more RAM when I switch from Normal Mode to Gaming Mode. Sims 3 seemed to play a bit better. There is no cost involved in using Game Booster.