Re: Redisplay slower in Emacs 28 than Emacs 27

[Alan Third]

On Mon, Dec 07, 2020 at 10:15:43PM +0100, Lars Ingebrigtsen wrote:
> Gregory Heytings <ghe@sdf.org> writes:
> 
> > 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.

As far as I can tell the "!" makes no great difference to the toolbar
images as it somehow finds a matching image in the cache anyway.

-- 
Alan Third