A patch released last week for Team Fortress 2 has finally added multi-core support allowing players to enable quad-core processing for improved performance. You might be wondering why this feature was just added especially since Left 4 Dead has had it since launched. While Valve only has one engine, the Source engine, there are different versions for each game.
The Left 4 Dead engine has had multi-core support since launch as well as the new particle engine because the game was more performance intensive but what the Left 4 Dead engine didn’t support was DirectX 8. The Orange Box engine, which Team Fortress 2 runs on, does and porting it to the Left 4 Dead engine would then disqualify certain player’s computers from running it. So Valve had to go back and edit the Orange box engine to support multi-core.
Depending on your commuter set up, enabling multi-core support (Options -> Video -> Advanced) could increase your FPS up to 15fps.