Optimization?

[The chaser]

You can add culling fog to your level, just a very faint fog. When using sounds and particles, you can do this too:

http://wiki.frictionalgames.com/hpl2/amn...erformance

PreloadParticleSystem(string& asPSFile);
PreloadSound(string& asSoundFile);

These two Preload a Particle system or a sound, and when you use them, they cause less lag.