Re: Redisplay slower in Emacs 28 than Emacs 27

[Gregory Heytings]

> > > That being said, it seems to me that this slowdown is avoidable. 
> > > Lars considers that the minor modification he made should not have 
> > > changed anything.
> >
> > Would it be possible for you to run the benchmarks on the current 
> > trunk, with and without that "!"?  Because I just don't understand why 
> > disabling the image cache would make Emacs slower.
>
> Sure, I'll do that.

I just did this on revision fc54c835 (Dec 5).

With equal_lists 18.7s, with !equal_lists 16.1s.

This difference is not due to an obscure compiler bug, the timings above 
are with GCC 10, but the timings with Clang 9 are similar: with 
equal_lists 19.0s, with !equal_lists 16.6s.

The difference vanishes when the toolbar is disabled: with equal_lists 
15.6s, with !equal_lists 15.7s.