@Stefan
> FWIW, a PGO build of Py3.7 is now about 20% *faster* here than my Ubuntu 16/04 system Python 2.7

Does that mean we can close this issue? Or do I misunderstand what you are comparing? 32 vs. 64 bits? PGO vs. non-PGO?

OTOH on my Mac I still find that 3.10 with PGO is still more than twice as slow than 2.7.

Thinking about it that's a bit odd, since (presumably) the majority of the work in sum() involves a long int result (even though the values returned by range() all fit in 30 bits, the sum quickly exceeds that).

(earlier)
> I suspect that adding a free-list for single-digit PyLong objects (the most common case) would provide some visible benefit.

If my theory is correct that wouldn't help this particular case, right?

FWIW just "for i in [x]range(15, 10**9, 15): pass" is about the same speed in Python 2.7 as in 3.11.