I have a late 2009 8 core Mac Pro, 48 gigs of ram, and a 4 gig video card. (Quadro K5000) Everything works fine and I can play 5k R3D files realtime at 1/4. But when I am using scopes, they lag 3 or 4 seconds behind when advancing a frame at a time. Also, I can usually hold down an arrow key to scan froward or back, but with scopes open I can only advance a frame, wait 3 or 4 seconds for the scopes to catch up, and then advance another. It was never like this before!