Raku is also, unfortunately, the slowest language I've ever used especially, paradoxically, for regex and string handling given its Perl lineage.

Lua doesn't have a GIL, either.

The tcl threads are shared nothing with message passing...each thread is a separate interpreter. So it's not obviously better or different than any other language running multiple processes with message passing via mmap or similar.

nmap has a serialization cost, and sharing complex data structures is hard with it.

It's also different than multiprocesses as it will likely take less RAM.

Python is explorer multiple interpreters for these reasons. Python 3.8 SharedMemory works well, it's far from transparent.

>mmap has a serialization cost

It does, though there should be optimized ways to do that if it's message passing and not object passing.

Indeed, Raku does not have a GIL

PHP is GIL-free too.

Perl is GIL-free too, actually.