I looked my problem up on the forums and I can see others have had this problem too, however, I don't think I should be having it because I definitely didn't have hardware as old as theirs. (My computer was only purchased in Nov. of 2008...)
It's got an Intel Core 2 Duo 2.4ghz processor with 2gbs of DDR2 RAM, and a Palit Radeon HD3850 1gb. I'm running Windows XP Service Pack 3 and my resolution is only set to 1024x768 because I only have a crappy 17" CRT Monitor.
I have Nexuiz running on max everything, and it runs perfectly on pretty much all maps, however....there are some maps (ex: "Batcula", or "q3skoredm1") where it works ok most of the time, but the second I look into certain rooms there is a massive framerate slowdown from, let's say the usual 70-90fps to about 14-19fps. This usually only happens for a few seconds and it goes back up to around 20-30fps, but my controls same to lag in the process as well. I can tell it is a graphic problem though.
I've tried lowering the Effects from Ultimate to Ultra...no go, same problem.
Tried lowering from Ultra to High, problem solved, no more drops, however...my hardware is good enough to be able to run the game maxed all the time...isn't it?
I can run new games such as Race Driver: GRID on max in 1024x768, why is Nexuiz being stubborn? Any thoughts, or am I just having overzealous belief in my hardware...?

Thanks!