I read a post on the subject a long time ago but unless I am mistaken its an either or situation. What I mean is, if you turn on all of those setting in your video card setting before the game they will only remain on and functioning untill you press shift+PGUP. You are running at Anisotropic filtering: 16x Anisotropic optimization: OnAnisotropic sample optimization: On Antialiasing setting 8x untill you press shift+pgup. As soon as you press that it turns off everything you turned on in your video card before game, and turns on HDR or whatever setting that thing affects. So you have HRD (or whatever that key combo turns on) but you no longer have Anisotropic filtering: 16x
Anisotropic optimization: On Anisotropic sample optimization: On Antialiasing setting 8x. You cant have both at the same time. With all of those setting turned back off and only HRD (or whatever it is) running your FPS may be going up because its not taxing thevideo card as much. Hit shift_PGUP again to turn it back off and you go back to Anisotropic filtering: 16x Anisotropic optimization: On Anisotropic sample optimization: On Antialiasing setting 8x, and that may be more than your card can handle. Someone correct me if I am wrong because I would like to have this clarified as well.