CPython already has a lower latency GC than PyPy, gc.disable() already works, and allowed manual memory management when needed.

Reference counting allows you (if needed) to keep references to memory in your python code, and free them in the right spots.

This is PyPy becoming useful for a lot more production use cases. From web APIs that have a latency SLA, to audio, games. In many cases peak performance is not important, it's the minimum performance.