Problems with lag/stutter watching Blu-Ray 3D movie

[AndyW1384]

I'm having lag/stutter problems watching a movie.

I'm watching from Blu-Ray 3D, not ripped, via Media Player Classic, in over/under.

(https://www.tchapin.com/how-to-watch-3d-blu-ray-movies-on-the-htc-vive-or-oculus-rift-without-having-to-re-encode-the-movie/)

Win-10 home 64, Oculus Rift S, NVidia GTX 980, Core i7-4970K, 16GB memory. I've turned off/down all the graphics options in Bigscreen that I could find, and Bigscreen reports supersampling as set externally. I'm launching Bigscreen from Oculus Home.

When playing a movie, on the monitor playback is smooth, but in Bigscreen there is a regular slight stutter. Smooth panning shots are slightly nauseating because the stutter looks like a slight backwards hitch about once or twice a second, and action scenes give an impression of jerkiness. This wasn't happening the last time I did this (though that was a few months ago on Rift CV1).

No other visual artifacts, and my network connection is wired.

Does this sound like a settings issue?

[Jericho]

Me too laggy movies! dropped framerates. wasn't happening till 2 days ago. I am using 1080gtx 16gb 3000khz ram i7 7700 wired 2png 20mgb upload 70mgb download