Re: Redisplay slower in Emacs 28 than Emacs 27

[Gregory Heytings via "Emacs development discussions." <emacs-devel@gnu.org>]

>>>> 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.
>
> Could you also try with this patch:
>
> @@ -2351,7 +2356,7 @@ lookup_image (struct frame *f, Lisp_Object spec, int face_id)
>
>   /* Look up SPEC in the hash table of the image cache.  */
>   hash = sxhash (spec);
> -  img = search_image_cache (f, spec, hash, foreground, background, true);
> +  img = search_image_cache (f, spec, hash, foreground, background, false);
>   if (img && img->load_failed_p)
>     {
>       free_image (f, img);
>
> It's a definite mistake on my part and may affect the caching of images, 
> although I can't see any way that it would slow anything down.
>

That doesn't fix the problem: 18.7s without this patch, 18.6s with this 
patch.