Sure, but Guido put a pre-condition on GIL removal years ago that it must not cause single-threaded code to suffer a performance penalty.

So Sam came up with a way to ensure that (on balance, if not in every example), we could have same-or-better performance and no GIL. Awesome!

But now we're getting the performance boosts without the GIL removal, and so in the next release, the GIL removal will cause a performance regression unless we can somehow find more performance boosts. It feels like this could just happen forever.

There's many more improvements to be made in single threaded performance, including things like JIT. Future improvements are complicated, they won't be a free lunch like this first round has generally been. My feeling is that things like JIT and nogil will start out as optional and work their way into the ecosystem over time where the performance implications are less severe for the general use case.