Hi @tramchamploo,
friendly: you simply made a database benchmark, and you made it wrong.
The fun a and the fun c are different, so results are not comparable.
The fun c is right after the `fun a, so I can suppose that the database is entirely in the ram disk buffer, so the result is not comparable.
The fun a and fun b start using a cold JVM, so everything run later it will run faster.
CommonPool and ForkJoinPool.commonPool have different number of thread, so parallelism is different and the result is not comparable.
Finally you must not use a cpu bounded thread pool for blocking operations, your 386 can send hundred of SQL update without any issue, so use a different thread pool, but you should never use CommonPool or ForkJoinPool.commonPool.