The quick and dirty workaround is to change ur detail level (low/med/high) and back again.
If you have an ATI card then there is a permanent fix since the newest ATI drivers' OpenGL don't like KOTOR2.
What you do is:
- get the 4.11 exe and open it with winzip
- get a file called atioglxx.dl_
- use the command prompt to type "expand atioglxx.dl_ atioglxx.dll" OR just open it with winzip also.
- take the resulting atioglxx.dll and put it in your kotor2 folder
this makes the game use the 4.11 openGL drivers.
It was a big thing for fixing the slowdowns and/or corrupt graphics permanently (with an ATI card)
hope it helps