Well, actually Serhiy is right, it does not seem that the macro benchs did show something significant. Maybe the code can be used in other parts of CPython, for example in _pickle, where dicts are loaded. But it needs also to expose, maybe internally only, dictresize() and DICT_NEXT_VERSION(). Not sure it's something desirable.

There's something that I do not understand: the speedup to unpack_sequence. I checked the pyperformance code, and it's a microbench for:

a, b = some_sequence

It should *not* be affected by the change. Anyway, I run the bench other 10 times, and the lowest value with the CPython code without the PR is not lower than 67.7 ns. With the PR, it reaches 53.5 ns. And I do not understand why. Maybe it affects the creation of the dicts with the local and global vars?