If you have a Dual Core AMD or a Duo Core Intel PC, and you try to play UT on it...its gonna lag and skip like crazy. 

Someone has made a fix that forces UT to run on 1 Core. 

Here's the fix: 

http://www.ut-files.com/Utilities/Dual_Core_UT_Fix.zip 

I believe Cali and Godzilla went through this trouble. To bad we didn't find this sooner.