I’m not talking about playback lag or video responsiveness. My issue has to do with interface lag. Clicking on a menu induces a delay. Adjusting a keyframe on any audio-only clip induces a delay. Clicking and dragging a color solid from one bin to another induces a delay. All interface interactivity has the lag delay. Let’s talk about the machines that are not in my suite that are involved: The iMac Pro in Edit 8 is experiencing this same lag issue whereas another iMac Pro in Edit 1 with exactly the same setup; OS, software, plugins, and fiber channel connection to the SAN is not. I do not suspect the media. Last week I was working with 8k REDcode files that take a moment to display, heck our biggest film right now is 10k by 2k and that works fine (though obviously, that film drops frames during playback which is not the issue I’m reporting here). The project files are tiny, under 1.5 MB. Yes deleting everything in the project file does alleviate the problem but that isn’t a workaround, obviously.