Originally Posted by Revs
What makes you think it wouldn't lower your frame rate? DX11 opens up new features that your GPU has to render. If you don't think the extra effects are worth the FPS, just use DX10. As for the slow loading times; that's a problem which will be sorted some time soon I'm sure. But you can't blame that on DX11. That's down to drivers. ATI had the same problem but updated drivers sorted it.
BFBC2 and Dirt2 both run smooth as butta @ 1900x1200 maxed out on my rig. Yeah driver updates definatley helped out ATI's performance here. I'm sure Nvidia will get it together soon w/ the fermi drivers.