I just noticed today what a difference checking the smart-render tab in ConnectHD makes in Vegas's preview window CPU-wise. On my P4 It looks like it takes a little more than twice the CPU power to preview the Cineform video when this tab is not checked. It may not be even a noticable blip to someone working with a Core Duo setup, but on my single core P4, it's the difference between dropping frames and a smooth preview.