Samuel Greear has graphed out the performance of both MySQL and Postgres on DragonFly 2.12 as you add threads. There’s a very nice correlation on performance and number of cores. For comparison, there’s this old test from 2007 which shows uniprocessor performance to be good but not improved by adding cores. The tests were on completely different hardware, so the actual curve of the graph is the telling point.
As he points out in his post, excellent multiprocessor performance is arriving on DragonFly, without any catastrophic shifts or destabilizing changes.