Hello alons_y,
We need to rule out all possible possibilities (your hardware etc ) vs my practice (if you asked me), so:
lets try 1st:
Are you on low-end PC, laptop?
If so try:
about:config
dom.ipc.processCount 1
note: no worries, you only change performance, (just 1 core), not about privacy etc
for example: my last success solution (antiX 64bit(32bit success) sisVinit core) was: 1 stupid wrong variable in zram script /bash illegal > boot/reboot/halt
I meant, You never know, need try from…