bug#27350: #27350 25.2; Make `inhibit-compacting-font-caches' customizable

[Eli Zaretskii <eliz@gnu.org>]

> From: "Felix E. Klee" <felix.klee@inka.de>
> Date: Thu, 15 Jun 2017 17:46:25 +0200
> Cc: 27350@debbugs.gnu.org
> 
> > However, what we really want is not the list of all the fonts, but
> > only those fonts which slow down redisplay.
> 
> Everything is slow. Even navigating point over the Latin (Courier)
> characters is slow.

Even if you shrink the window so that only Latin characters are
visible?

> > I see no perceptible slowdown.
> 
> Maybe your system is faster.

I sincerely doubt that.  This box is 5 years old, it cannot be too
fast by today's standards.

> If you could post the necessary config lines, that would be great! The
> font is installed on my system.

OK, will do later.  As a first approximation, try this:

  emacs -Q -fn "Arial Unicode MS"

This will make that font the default font, and Emacs should also use
it for most/all the funny characters that are supported by Arial.  I'd
be interested to know if this is still slow.