On Saturday, July 17, 2021, Andrea paz <gamberucci.andrea@gmail.com> wrote:

Thank you for your interest in an issue that's killing me!
Applied the patch; it seems to always show cpu 16. I have an 8c/16t so
it is shown fine.
I attach cpu-count.txt to show output during playback and rendering operations.
A video of the above operations can be found at the following address.
https://www.dropbox.com/s/m4bpa0y9mk55btq/cpu-test.mov?dl=0
Note that today it went better than the average I normally have: in
playback I had less freezes and in rendering I got an average of 60
fps, while normally I stay on 12 fps.

one possible explanation, if you have cpufreq set to 'dynamic' /powersave it may not reclock cpu (and memory/bus?) fast enough.. so encoding stuck in low freq. mode (i think some games behaved similary) try to force 'performance' mode.

Last note: from a 10 years ago laptop with a good i7 4c/8t I switched
to an AMD 8c/16t with double the frequency. For example to compile
CinGG (with all 8 threads in Intel and with all 16 threads in AMD,
always at 100%) I went from 20 min to 5 min. Instead in playback and
rendering I don't notice big differences.
Using a rendering via handbrake or ffmpeg from command line is
extremely more efficient.