25.2.0 build 21 Lumetri causes stuttering playback

Ryzen 3960X 24 core, 128GB of Ram, 2080Ti/11GB; OS/programs on one Nvme drive, all cache files on the second Nvme.

All media and projects on internal SSDs. 

Media is 1920x1080 AVC-Intra from a Panny GH3 in mov. Not long-GOP.

Adding ONE Lumetri effect to the clip causes the bar to go into red and stutter to occur.

I've never had stutter with this simple media before (even on my laptop!) with mutliple Lumetri effects applied to a clip. So this was surprising. This is a test sequence that always plays like butter.