I would have liked to post screen shots but didnt take any this is something you can try
for your self.
Run game push CTRL + left shift + F to bring up the FPS
check your FPS then remove the HUD do this by pushing ALT + Z (your fps shows bottom left of the screen)
The FPS counter will still show after you remove the HUD now according to my machine it jumps up 20-30 FPS when i remove all of the hud, i had seen other posts saying there was a loss of FPS when the companion window or inventory was open so i decided to test the hud and was amazed at the gain in FPS from simply removing the hud options.
For some wierd reason your still able to click on the hud or ui options what ever you prefer to call it.
So why am i posting this to what end will come of it, absolutely nothing will come of it but if it helps a few people out there then good.
one other thing i should mention when i done this i was not moving about just standing still butt non the less it does raise the fps.
No im not suggesting we all run about with no HUD but for the people on 10-15 fps every little helps.
Here is a link to another supposed Fix to gain a small ammount of fps it worked for me it may not work for every one it seems to be 50/50 from the comments i read.
http://www.microsoft.com/download/en/details.aspx?id=8109
Create new folder any where (desktop) extract and run DXSETUP
Here is the link to the site where i read the comments.