tmpfs(5) not fully MPSAFE
Bulk building packages with ports-mgmt/poudriere on a 16 cores/32 threads machine is very slow.
The system exhibits high level of mp_token contention.
The functions grabbing it the most are:
vop_inactive vop_readdir vop_setattr vop_ncreate
vop_close vop_nresolv vop_nlink vop_putpage
with vop_inactive() by far the worst offender.
As the only non fully-MPSAFE used filesystem, tmpfs(5) is an obvious culprit.