It can be configured to use the system malloc (IIRC running stuff like asan requires this, or at least I have to set a 'no jemalloc' build option), but I'm not

It can be configured to use the system malloc (IIRC running stuff like asan requires this, or at least I have to set a 'no jemalloc' build option), but I'm not sure if any platform ships with this option turned on. OpenBSD sounds like one that might, but I guess I thought they just used the normal Firefox ESR (definitely could be wrong though).