Concurrent operations exist at all levels of the software stack. Just because native extensions might want to release the GIL and use OS threads doesn't mean pure Python can't also want (or need) that.

(And as a side note: I have never, in around a decade of writing C++, heard std::thread described as "easy to debug.")

Really? Cool.

I expected that dropping down to C/C++ would be a large jump in difficulty and quantity of code, but I've found it isn't, and the dev experience isn't entirely worse, as, for example, in-editor code-intelligence is rock solid and very fast in every corner of my code and the libraries I'm using.

If anyone could benefit from speeding up some Python code, I'd highly recommend installing cppyy and giving it a try.