Does anyone know if there is more serious single threaded performance degradation (more than a few percent for instance)? I couldn't find any benchmarks, just some generic reassurance that everything is fine.
There have been patches to remove the GIL going back to the 90s and Python 1.5 or thereabouts. But the performance impact has always been the show-stopper.
This post is a call to ask people to “kick the tires”, experiment, and report issues they run into, not announcing that all work is done.
So the net is actually a small performance win but lesser than if there was no free threading. That said, many of the techniques he identified were immediately incorporated into CPython and so I would expect benchmarks to show some regression as compared with the single threaded interpreter of the previous revision.