For those of you playing at high+ graphics on a graphic card that cant handle a few hundred thousands extra polygons, you most likely end up with huge lag in uz compared to anywhere else.
The issue is indeed in the background (someone thought it would be cool to use a huge 3d model repeated hundreds of times >_>)....
Heres a simple fix to disable it on your client until i can get someone to actually look at it and fix it for real (as in have the background without all the unnecessary weight).
http://www.starsonata.com/jey/uzlagfix.zip this zip contain a Content folder. Extract it in your star sonata directory as to overwrite the Content folder. It use the skin system and as such will stay even after patches.
You will need to delete the uzlagfix directory from your Content dir, if you wish to remove the hack.