There are too many variables to give a straight answer. Writing to a bunch of different files at the same time? Postgres is probably faster since all that disk

There are too many variables to give a straight answer. Writing to a bunch of different files at the same time? Postgres is probably faster since all that disk IO contention gets turned into a write to the WAL. Don't have the resources to give postgres? Files maybe faster than watching pg choke on a lack of RAM or CPU time.