bug#75342: [PATCH] Speed up asynchronous man page fontifying

[Eli Zaretskii <eliz@gnu.org>]

> From: Björn Bidar <bjorn.bidar@thaodan.de>
> Cc: Stefan Kangas <stefankangas@gmail.com>,  75342@debbugs.gnu.org,
>   juri@linkov.net
> Date: Sat, 04 Jan 2025 11:33:18 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> When I set `Man-prefer-synchronous-call` to t, it takes ~1.8 seconds to
> >> process the same page.  I guess that this is the lower bound for how
> >> fast we could make the asynchronous call.
> >
> > Why not make Man-prefer-synchronous-call t by default, then?
> 
> The call might take longer on slower machines (or network connections)
> and then block Emacs until the call was done.

Slower connections (I'm guessing you mean remote man pages?) could be
recognized exempted from synchronous operation.  As for slower
machines: this is a defcustom, so users of slower machines can
customize it if the synchronous formatting is too long for them.

> Never block ui unless you can do avoid it.

Except that this comes at a price here: the time until I can see the
full man page could be very long.  So this is not a back-and-white
situation.