Re: Redisplay slower in Emacs 28 than Emacs 27

[Gregory Heytings]

> > > 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.
> >
> > Very interesting.  Using the image cache for small images slows Emacs 
> > down?  Or is there a bug in equal_lists?
> >
> > Just to make 100% sure -- could you re-run the benchmark with something 
> > like the following as the function:
> >
> > static struct image *
> > search_image_cache (struct frame *f, Lisp_Object spec, EMACS_UINT hash,
> >                     unsigned long foreground, unsigned long background,
> >                     bool ignore_colors)
> > {
> >   return NULL;
> > }
>
> I already tried that and it absolutely killed Emacs when the toolbar was 
> displayed.

Not on my computer.  I changed "if (!c) return NULL;" into "return NULL;" 
and it worked.