Hi Folks,
Some of you may know about this fix, but I was really upset at the frame rates until I realized what the problem was.
This is for you Nvidia folks that may be wondering why the game is running slow.
I downloaded the steam demo, and part of the installer installed the newest version of Physx, problem is that is installed in in CPU mode, so the game was not using the GPU to render the physics (overloading the CPU and causing low frame rates).
The simple fix for you NVIDA Steam demo folks that may be in the same boat is to uninstall your physx and reinstall Physx manually from your Mafia II steamapps folder under the 3rd folder
In my case it was here:
C:\Program Files (x86)\Steam\steamapps\common\mafia ii - public demo\3rd
Now the game runs rock solid 60 FPS and now the game is amazing. Cars are easier to drive, and the Shooting is easier to target (along with amazing visuals)
Good luck, if this helps one person my work is done