Subject: bug#14966: 24.3.50; Char-displayable-p is a very long running function

From: Stefan Kangas <[email-masked]>
Date: Wed, 18 Nov 2020 07:24:21 -0800

Eli Zaretskii <[email-masked]> writes:

>> From: "Sebastien Vauban" <[email-masked]>
>> Date: Mon, 29 Jul 2013 10:10:36 +0200
>>
>> I'm striving for a sub-second Emacs startup time, I'm only
>> interested in the first time...
>
> The usual way of solving this is to start Emacs only once, and leave
> it running at all times.

The reported problem is that `char-displayable-p' takes too long to run
the first time it is called after starting a fresh Emacs.

The recipe is:

0. emacs -Q
1. (benchmark-run 1 (char-displayable-p ?\u25B7))

(The above takes 200ms here.)

Is this something we will want to do something about or is this all
working as expected?  The discussion in the bug report suggests that
this is indeed something that we can live with.