http://www.shsforums.net/topic/48732-ddraw-fix-for-slowdownsstuttering/

Downloading this should solve most of the problems that arise from running PS:T on new machines. It ran smoothly on my Win 7 using this. I posted this in another thread, but I feel it is useful enough to create its own thread and hopefully a sticky to help people out.

Oh man this is great! It worked just fine, solved my problem on my mac. I'm using parallels.
Thank you very much!

Solved my problems too, only I used the alternative method with WineD3D DLLs. Thought that they were easier to roll back in case they didn't work.
Only two drawbacks:
- Starting the game takes about 8-10 seconds
- Windows does not draw any other windows (except for Process Manager), so can't Alt+Tab to the browser.

Thanks. This seems to have fixed the mouse stuttering :)

How do you use this fix? I just unzipped it into my Torment folder, but it has no effect on the stuttering of my game...