Yes this makes sense a suddent 10/20FPS drop, it feels like a Ram problem but could be this I suppose?
Lower your shadows to medium, turn HBAO off too.....HBAO even dropped fps by 10-20 in BFBC2 on high end cards.
Why are some people here only using 8xAF? whack it to 16x, it uses hardly any vram.
Motion Blur is always off for me in every fps i personally do not see the point of it.