I’d like to improve the speed that I edit multicam in FCPX from original h264 camera files. With 1080p it works fine but as soon as I add a 4k camera even if it’s only a two camera it slows to a crawl and drops frames. I’ve tried: 1. Switching to performance instead of quality preview with little effect 2. Creating a proxy helps but its time consuming to transcode and I don’t like 1080p when it’s proxied 3. Transcoding to ProRes is the best but once again takes a long time to transcode and the file sizes get crazy. I work off 1tb SSD but 3hr video in 4k in prores fills up most of the drive. If for any reason you need to switch to another project I’m left with an unenviable task of moving off those huge files to a spinner drive then moving them back or to delete the transcode and then re encode. Both can be overnight tasks. My current Mac Pro I’ve upgraded the cpu to fastest offered and I upgraded to the Radeon 5870 which was a huge improvement. I’d like to upgrade the video card to 7950/7970 or the 280x or 580x pulse. It’s not a matter of money but whether it will speed up playback that I can edit properly. I’ve seen Apple has added support for 580x but if that support is contingent on High Sierra that’s a problem because DVDSP is no longer supported along with issues with Adobe CS5. So that then leads me back to 7950/7970 and whether it’s fast enough to handle 4k. I could buy a new imac or build a Hackintosh but I’d have the same issue being able to author dvds. I also don’t want to maintain two os and switch between them. I apologize if I’m re asking a previously answered question. I have read threads on similar 4k issues with macpro towers.