This isn't a problem specific to python though. You hint at it, async programming (single thread worker loop) is not the right way to deal with CPU-bound tasks.

This isn't a problem specific to python though. You hint at it, async programming (single thread worker loop) is not the right way to deal with CPU-bound tasks. NodeJS or any other async language would have the same problems. You want multiprocessing or multithreading, where work is distributed to different CPU cores at the same time. Python gives you the ability to use any of those three paradigms. Choose wisely.