Videomaker – Learn video production and editing, camera reviews › Forums › General › Video and Film Discussion › Advice new program/ win/mac › What kind of video are you
What kind of video are you doing? HD, 4K? It may be how your system is handling the video. In Final Cut X, the source files are transcoded into ProRes 422, based on what the timeline is, which makes things much more easily handled by the editing system. If your computer is trying to play back the original files, especially those heavily-compressed mp4 files, it might be choking on them. The system you have seems pretty beefy, so I don’t think it’s the hardware.
Also make sure your hard drive has plenty of free space so it’s not hunting around for the next clip.