Whenever I read stuff like this my inner optimiser starts wondering where the CPU is going and why - massive GC cycles, inefficient regexp stuff, poor algo choice, bad cache locality, etc etc.
At the risk of ill manners but i must ask, have you looked at all this because I've got in some cases orders of magnitude speedup by popping the hood and instrumenting.
So much so that I’m now trying to figure out whether we can somehow cheaply move to a dual Epyc 7742 setup.