Depending on your video card, this may or may not help your frame rate much

Open your console
Type in command:
fps_max 100

*NOTE* Depending on current settings, the results could be anywhere from huge difference to minor change in shadow


Open console
type in lightgamma 0
play!

This must be entered in every time you start your game, so it helps to bind it to a key!
To display numbers along with dots for latency on a server type -numericping in the shortcut's target line.

To turn off background sounds so you can hear footsteps and real fire better type stopsound in the console.