Re: Redisplay slower in Emacs 28 than Emacs 27

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: ghe@sdf.org,  emacs-devel@gnu.org
> Date: Tue, 08 Dec 2020 17:31:16 +0100
> 
> So moving to Fequal is fine if we decide to have the Emacs 27 caching
> semantics.
> 
> However, if we move to EQ semantics, the real speedup is that we don't
> have to call sxhash(img) on all the images -- and that's a slow
> operation, because it'll call hash_string on all the string contents,
> and if you have a large :data image, it'll compute that every time Emacs
> decides to redisplay that image.

I don't think I follow: since an image spec can (and usually does)
include a file name, how can we use EQ?  That would mean identical
file names will cause us to think an image isn't cached, right?  Or
what am I missing?