Main Concept for me is the slowest of the two, GPU or CPU, more so when selecting the GPU. It usually gets around 25FPS, and after about 3 seconds worth of rendering, it’ll pause for a few more before continuing on, etc.
Sony AVC is what I’ve been using (GPU).
Regardless, render times are much slower than when I have a GTX 560. It’s not a deal breaker, but it’s had me considering Adobe Premiere, although I heard that that’s noticeably slower than Vegas in most areas. My videos are simple and don’t need anything hardcore, so I’ll probably just stick with Vegas and hope that they figure out a better way to take advantage of these cards.