So PG has a process pool instead of a thread pool. (I doubt either database is spawning procs/thds anew willy nilly for each request). This means the PG has

So PG has a process pool instead of a thread pool. (I doubt either database is spawning procs/thds anew willy nilly for each request). This means the PG has explicit IPC overhead, vs the quick and seductive path (to the dark side?) of simply sharing memory between threads. Safety vs speed.