bug#69385: 30.0.50; Long lines with bidi text slow down Emacs

[Eli Zaretskii]

> Cc: 69385@debbugs.gnu.org
> Date: Mon, 26 Feb 2024 16:19:15 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> 
> > From: Stephen Berman <stephen.berman@gmx.net>
> > Cc: 69385@debbugs.gnu.org
> > Date: Mon, 26 Feb 2024 15:13:38 +0100
> > 
> > On Mon, 26 Feb 2024 14:33:18 +0200 Eli Zaretskii <eliz@gnu.org> wrote:
> > 
> > > The CPU is fast.  My HarfBuzz version is much older, but I doubt that
> > > HarfBuzz became so much slower for Arabic.  So it's very strange.  But
> > > maybe it's worth to try downgrading to an earlier version, just to be
> > > sure this is not the culprit?
> > 
> > That's not so straightforward on this system, where I build system
> > packages from source, so downgrading HarfBuzz may require also
> > rebuilding packages that depend on it.  I have a somewhat older system
> > on this machine with HarfBuzz 7.1.0, so I can easily try that.  What
> > version of HarfBuzz are you using?
> 
> I have 2.4.0 here.

Btw, another possibility could be that this is specific to the Cairo
build.  So maybe try a build without Cairo.