Re: Redisplay slower in Emacs 28 than Emacs 27

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: ghe@sdf.org,  Eli Zaretskii <eliz@gnu.org>,  emacs-devel@gnu.org
> Date: Tue, 08 Dec 2020 20:36:47 +0100
> 
> +     case Lisp_String:
> +       val = (EMACS_UINT) SSDATA (obj);

Why use the pointer?  Lisp strings can be relocated, and there could
be another string with the same contents.  Why not support those?

> @@ -1649,7 +1650,7 @@ uncache_image (struct frame *f, Lisp_Object spec)
>       can have multiple copies of an image with the same spec. We want
>       to remove them all to ensure the user doesn't see an old version
>       of the image when the face changes.  */
> -  while ((img = search_image_cache (f, spec, sxhash (spec), 0, 0, true)))
> +  while ((img = search_image_cache (f, spec, img_hash (spec), 0, 0, true)))

Any reason you call img_hash in a loop with the same argument?

Last, but not least, a question: what kind of savings will this
produce, and why?

Thanks.