Wondering what system you’re on Bill. Optimized has never increased performance much for me. Just eats up space. Proxies would make sense for dealing with 4k, but in my tests with mxf, h264, avchd, I get minimal performance boost if any from optimizing. But I’m using an iMac. Seems that MacPro users seem to have more difficulty with h264 based formats because they don’t have the accelerated h264 encode/decode. As for h264 exports in HD, a 3 min timeline is often a matter of seconds to export. Maybe 1/4 to 1/3 the total of the timeline depending on complexity. But certainly much faster than actually rendering the timeline. And how do you almost have 5 years of experience with X? It was released 4 years and 2 months ago.