Just wanted to give feedback;
bossanova808s fix did the job on my old Intel NUC DN2820
so big thanks to bossanova808
Ok, more experimenting...and I think I have beaten it (or more to the point Ross Nicholson has it cracked, here: 111032 – Need to set gt_min_freq_mhz to max value to avoid sync issues on Gemini Lake N5000/J5005)
It seems this is (still) the problem. The GPU clock speed is not scaling up as it should under load.
With a NUC 2820, I added this `autostart.sh` script:
( echo 750 > /sys/devices/pci0000:00/0000:00:02.0/drm/card0/gt_min_freq_mhz ) & nohup script.sh &
The 750 comes from the output of this command (you should check if you have a different NUC)
This results in immediate playback improvement - the stutter is gone from all my 25p stuff.
(I updated the bios to 68, and I am in this test using the 9.2 alpha release but it was only this specific fix that had any impact on the issue).
If I test the GPU (i.e., specifically while playing a hardware decodedc video), with
...it now shows 750 during playback (187 during the Kodi GUI still, though, which kinda surprises me but I guess the GPU is idle until playback occurs maybe?)
I shall report back if testing shows any/more issues, but I think that's a solid fix, if anyone is still following along.