Well I using an old 8800 ultra and had no stuttering issues with the game.
Since you mentioned you had successfully installed the patch, I think you should had already notice those major improvement. Whether there are any more changes and improvements than those which had already been listed out, I had yet to discover them. Those might really need a new fresh start character to full experience the difference. I am too lazy to restart as my 2nd run through had already reach sentinel island when I apply the patch.
