some minor things you can do
1. Go to a gas station and blow the whole PC with those air things they have . you know for the tires :P
2. Disable windows 7 aero.
3. Download and run game booster
4. While running the game -> ctrl+alt+delete -> processes -> find your game -> show processes from all users -> right click and set priority to above normal or high. If after this the pc is unstable , make it normal priority again
5. Antialiasing always off and Vsync as well.