if it runs a bit laggy and slaggy on your rig which seems prety solid god knows what it'll do on my 360 i know i know completly difrant, but still it'll probably kill my 360. i dont want to start a flame thread.
There is something wrong with your install. I am currently playing this game and have ZERO load times or any lag at all. It's smooth as butter. Also this was the case with my previous card too, 3870.