Nic, thank you very much for testing to see the issues I got with the game,
I think it's a problem with the driver because the game was working great on WIN8.0 without any issues, and the issues started just right after I upgraded to WIN8.1 .
So from that the issues can come or from the OS, or from the Graphics card.
Now I do know from what others says on the Steam community forums which got other type of Graphics card and WIN8.1 that they have none of these issues.
And others who do have HD 4000 says they got the same problem and it was also worked good for them before on WIN8.0.
And yea the game is heavy in general, but if it was working great before, it should also work now I guess.