If you're worried about performance then much of your CPU time is probably spent in a C extension (e.g. numpy, scipy, opencv, etc.). Those all release the GIL s

If you're worried about performance then much of your CPU time is probably spent in a C extension (e.g. numpy, scipy, opencv, etc.). Those all release the GIL so already allow parallelisation in multiple threads. That even includes many functions in the standard library (e.g. sqlite3, zip/unzip). I've used multiple threads in Python for many years and never needed to break into multiprocessing. But, for sure, nogil will be good for those workloads written in pure Python (though I've personally never been affected by that).