There are many possible things which could cause this prob. Without knowing more about your Configuration we can only guess. <img src="/ubbthreads/images/graemlins/tongue.gif" alt="" />
First of all install the latest
Patch ! There is a bug in Verdistis causing the game to slow down. The patch should cancels this out! <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />
Second: Check your system temperature! (You know how to do it? There is an option for this in the BIOS!) If you have a too high system temperature your computer will automatically slow down, in order to avoid overheating...
...happens about 71, 72 degrees centigrade.
Third: Disable all other programs, such as Virus scan running in the background. This programs need much of your memory.
Forth: Turn down your screen resolution and details a bit! What you should do anyway is to turn your colour resolution to 16bit instead of 32!
Hope that helps
<img src="/ubbthreads/images/graemlins/wave.gif" alt="" />