bug#45379: 28.0.50; Degraded Performance of describe-buffer-bindings

[Eli Zaretskii]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Fri, 5 Mar 2021 20:44:33 -0800
> Cc: Juri Linkov <juri@linkov.net>, martin rudalics <rudalics@gmx.at>, Eli 
> Zaretskii <eliz@gnu.org>, 
>       45379@debbugs.gnu.org, Stefan Monnier <monnier@iro.umontreal.ca>, 
>       Stephen Berman <stephen.berman@gmx.net>
> 
> It turns out that we were doing unnecessary looping due to the above
> mentioned commit.  While working on this, I also found that we can get
> rid of an unnecessary call to char_table_ref_and_range, which should
> make this function run even faster.

I'm not sure I understand the reasons for each of the changes here.
char-tables are a tricky data structure, so I'd like to make sure this
change doesn't make our code subtly incorrect.

So could you please walk us through the proposed changes, adding
explanations for each part as you go?

(And what do char-tables have to do with describing key bindings,
btw?)

> I'm also copying in Kenichi Handa, who was the last to touch this code.
> Handa-san, please let us know if you have any comments on this patch.
> Thanks in advance.

AFAICT, you didn't CC Kenichi; I have now added him to the discussion.

Thanks.