For everyone's safety, put down the computer and back away!
Now, once you have pulled on the appropriate safety gear (rubber gloves, anti-static clothing, grounding cable and goggles - never, ever forget the goggles), delve deep into the bowels of your computer (try not to be too squeemish).
Journey to your Call of Duty folder, then deeper still (you may need a headlamp here) as you descend into the "uo" folder ... wait a minute. This journey is clearly not safe for the ill-prepared. Reverse direction and head back for the surface. What ever you do, don't go too fast.
Once there, continue to back away from the computer. I think that would be safe for everyone!
It turns out that that 1.51 upgrade couldn't possibly have anything to do with your computer running slowly. You most likely have some spyware or virus running that is causing your problem. The 1.51 patch updates the actual COD UO application and if it isn't running, it won't be causing problems.
Now, if you meant to say you are still having problems with UO running slowly, then Steele made the following post which may have some useful information for you. Be sure to read through the thread as there were a bunch of helpful tips as well:
http://www.mobclan.com/forums/upload/index...st&p=128775Good luck, be safe and frag on!