I have a 20 inch 07 iMac with a weak 2.0 intel core 2 duo and a radeon HD 2400XT. I want more frames per seine on team fortress since I'm getting into a competitive team I need as much fps I can squeeze out of my Mac. Currently using a config to make the game look ugly and it nets me an average 70 fps with highs of 150 and lows of 55. Any more tips? Can include general Mac optimization or source engine tweaks.