I thought I would create this thread, I didn't see one about this subject before and I am posting this at 1am in the morning after a 4 and half hour gym session. Anyways, these links below are to help optimizing your map and making sure that them FPS stay high.

http://developer.valvesoftware.com/wiki/Optimization_%28level_design%29

http://developer.valvesoftware.com/wiki/Optimizing_and_Checking_Your_Map

You use optimiziation just before you feel that your map is ready. Remember to check checking your map for any parts which bring your FPS down and also do play tests, it helps with the optimiziation part of your map.