For the past few weeks, my computer was randomly freezing for about 30 seconds. After a quick search, it became clear that it was a memory issue, even though my computer has over 32 GB of RAM…
> journalctl -k -b -o short-precise
Sep 23 09:39:38.873173 myPC systemd-journald: Under memory pressure, flushing caches.
Sep 23 09:39:41.632171 myPC systemd-journald: Under memory pressure, flushing caches.
Sep 23 09:39:44.072486 myPC systemd-journald: Under memory pressure, flushing caches.
Sep 23 09:39:50.630124 myPC systemd-journald: Under memory pressure, flushing caches.
Sep 23 09:40:18.142581 myPC kernel: upowerd invoked oom-killer: gfp_mask=0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), order=0, oom_score_adj=0
> journalctl -k -b --since "2026-09-23 09:39:30" --until "2026-09-23 09:41:30" \
| grep -iE 'oom|killed process|kill process|out of memory|memory cgroup'
Sep 23 09:40:18 myPC kernel: oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),cpuset=/,mems_allowed=0,global_oom,task_memcg=/user.slice/user-1000.slice/session-c2.scope,task=Isolated Web Co,pid=2666576,uid=1000
Sep 23 09:40:18 myPC kernel: Out of memory: Killed process 2666576 (Isolated Web Co) total-vm:10469216kB, anon-rss:7162184kB, file-rss:196kB, shmem-rss:1752kB, UID:1000 pgtables:54092kB oom_score_adj:200
As it turned out, the problem was caused by Firefox (Killed process Isolated Web Co). Fortunately, the solution was quite simple. I enabled the unloadOnLowMemory setting:
about:config → browser.tabs.unloadOnLowMemory →true
Since then, everything is running normal again. I also tried to identify a specific extension or website, which needed too much memory via
about:processes
about:memory
but it was nothing out of the ordinary. I guess I just had too many Firefox windows and tabs open…