Thanks!
Sort of resolved.
I went through the verbose log.
Found:
[WARN] SYSTEM DIR is empty, assume CONTENT DIR /home/pi/RetroPie/roms/psx/Silent Bomber (USA).cue
[INFO] Environ SYSTEM_DIRECTORY: "/home/pi/RetroPie/roms/psx/".
no BIOS files found.
Okay, odd, but lets just try putting a bios file next to the rom...
If I put the bios files in the same folder as the ROM the bios gets found and performance improves as expected. Aka: Audio gets more consistent and it does no longer randomly just hang.
This might not explain why it doesn't find the bios where it is supposed to be according to the docs. but then again who knows what I messed up when I set this up a few years ago. Point is the information from the log was accurate and helpful.
This log to be precise:
/dev/shm/runcommand.log
Previously I have only looked at:
/opt/retropie/configs/all/emulationstation/es_log.txt