Eli Zaretskii <eliz@gnu.org> writes:

> In any case, Alan's original report was for optimized builds, and he
> observed (although was later unable to reproduce) that Emacs 28 was
> slower than Emacs 27.  So the important part of this is to compare the
> performance of the optimized (-O2) builds and see if we have any
> degradation in Emacs 28 in that case.

Given the following file /tmp/timeit.el based on Alan's benchmark: