os::jvm_path() calls into dladdr (on Mac), which takes time.

I've seen as much as 10ms on cold system and regularly see 2ms (2% of startup time) (on Mac)

Maybe we can cache the path somehow (store it in a CDS archive?) or let the user pass it in, to avoid looking it up.

Observed on Mac OS X, but likely affects other systems, to different degrees (need to verify)