My understanding is that even with GIL removed today, Python is still not a performant language for cpu-intensive tasks, be it single core or multiple-core.

Python is better used as a glue language and leverage numpy etc to do the heavy lifting, numpy can work with multiple-core just like c/c++/rust languages can.

If you really need launch multiple python processes, the multiprocessing module came to rescue.

While not ideal, I don't see a showstopper to use Python for HPC's high and parallel computation needs at all.