Chances are that PostgreSQL will be more performant on FreeBSD, but that would require a wee-bit of very specific fine-tuning for specific workload pgsql is doing and it would ultimately be thanks to ZFS, which I think is default on FreeBSD ( would work on linux as well, if setup correctly ). See here for more info on how and why's - https://people.freebsd.org/~seanc/postgresql/scale15x-2017-p...