Don't think it's a bug but I play at 1920x1080 with EVERYTHING maxed and Timeslice shadows and animations turned off (put those 2 ON and you'll gain some FPS) with the rig in my sig and it's smooth as butter...some drops in FPS from time to time but nothing unplayable.

If you're used to over 40 FPs and then get 25-30...you'll notice it I guess.

Not a bug tho.

Gaming machine : Win7 Pro 64-bit | Phenom II X4 955 @ 3.7GHz | Sapphire HD 6950 @ 1536SPs | X-Fi Titanium HD | 6gb DDR2-800 | LG 23" LCD 1080p