I recently got this game working and while I currently have no game breaking issues I seem to have crappy performance and I would to know if there's anything I can do to increase that. First, I have disabled that shadow transparancy, read somewhere you could do that and I have all those recommending mods from the mod guide.

I have a fairly modern computer which I belive could be the reason specifically that I have a quad core and perhaps "too new" drivers.

Yes your computer is too new probably.

Follow the instructions in this thread: http://www.shsforums.net/topic/48732-ddraw-fix-for-slowdownsstuttering/

The game ran like crap on my windows 7 netbook, but with the libwine.dll, wined3d.dll and ddraw.dll from the wine3d.exe file (open with 7zip) in the torment game directory solved all problems and the game runs excellent now!

I found the draw fix just after I created the thread and tried playing some. It seems to be gone now and I've no graphical artifacts as well, really neat. :)