FinalCut 10.8.1 Playback Issues after adding/editing keyframes

I'm seeing a recurring issue with multiple projects in FC 10.8.1 where playback in the timeline gets choppy or locks up entirely after adding or editing keyframes.

Specifically, I'm adding and moving around position/scale keyframes to a video clip in the timeline using the transform tools in the inspector. Immediately, the timeline does not playback smoothly or freezes. Force Quitting FC and re-opening fixes the issue, but it may happen again at random times.

Working on a 2018 Intel Macbook with Sequia 15.0. FC Libraries and media are all on a Samsung T9 in APFS.