I have Canon 5D mark 4 and it can shoot 4K videos in MJPEG format. When i tried to edit this video in FCPX it seems laggy and not smooth. I think it's about for MJPEG format because it's normal in the camera screen playback . And 1080P ALL-I & IPB videos are seems normal and ok too in Editing or viewing softwares. Do you have any suggestions to solve for this issue ? By the way thats problem not just happen in FCPX it is the same in Prewiew, Quick time and etc. players
It is a big codec to decode. Try this. Run a short clip through Compressor and convert to your preferred flavor of ProRes. Import that into FCPX. How does the clip perform? Or you can have FCPX convert to Proxy files and then link back to master clips for color grade.