Mercury Transmit - causing stuttered viudeo playback - Random Issue

I have 13900K on a Z690 using NVidia 2070 Super GPU Win 11 64 bit, 64GB RAM.

Solid State NVMe drives

Two 4K monitors driven from the 2070. I noticed choppy /stuttered video and spent ages trying to debug it - then as a last resort disabled and re-enabled Mercury Transmit and it went away.

When disabled the playback on main project window is smooth.

I use the second monitor as large screen to monitor playback normally.

Randomly it can appear again on the second monitor a few seconds later.

A cold restart seems to cure it for a while then it comes back at random.

All drivers up to date, Nvidia and GPU.

On Premiere 23.5.