Re: The Emacs master is much slower than the emacs-27 branch.

[Stephen Berman]

On Fri, 04 Dec 2020 18:31:48 +0200 Eli Zaretskii <eliz@gnu.org> wrote:

>> From: Stephen Berman <stephen.berman@gmx.net>
>> Cc: acm@muc.de,  emacs-devel@gnu.org
>> Date: Fri, 04 Dec 2020 17:03:00 +0100
>>
>> > Thanks.  This is very strange.  What are the build options and the
>> > features in each build? are they identical?
>>
>> emacs-27:
>>
>> system-configuration-options
>> "'CFLAGS=-Og -g3' PKG_CONFIG_PATH=/opt/qt5/lib/pkgconfig"
>>
>> system-configuration-features
>> "XPM JPEG TIFF GIF PNG RSVG SOUND DBUS GSETTINGS GLIB NOTIFY INOTIFY ACL
>> GNUTLS LIBXML2 FREETYPE HARFBUZZ XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11
>> XDBE XIM MODULES THREADS LIBSYSTEMD PDUMPER LCMS2 GMP"
>>
>> master:
>>
>> system-configuration-options
>> "--with-xwidgets 'CFLAGS=-Og -g3' PKG_CONFIG_PATH=/opt/qt5/lib/pkgconfig"
>>
>> system-configuration-features
>> "XPM JPEG TIFF GIF PNG RSVG CAIRO SOUND DBUS GSETTINGS GLIB NOTIFY
>> INOTIFY ACL GNUTLS LIBXML2 FREETYPE HARFBUZZ ZLIB TOOLKIT_SCROLL_BARS
>> GTK3 X11 XDBE XIM MODULES THREADS XWIDGETS LIBSYSTEMD PDUMPER LCMS2"
>
> Could Cairo be the factor here?  Emacs 27 was built without it.

On Fri, 04 Dec 2020 11:49:25 -0500 Stefan Monnier <monnier@iro.umontreal.ca> 
wrote:

> Hmm... so in Emacs-28, "you" removed XFT and GMP and replaced them with
> CAIRO and XWIDGETS.
>
> I doubt GMP and XWIDGETS make any difference, but maybe XFT or CAIRO
> have something to do with the difference.
>
> It might be worth fiddling with `--with(out)-xft` and
> `--with(out)-cairo` to see if you can get closer to the origin of
> the difference.

I can try that, but since I used the default configuration features,
that suggests that those who got no difference between emacs-27 and
master with the benchmark, or where emacs-27 was even faster, built
emacs-27 --with-cairo and --without-xft.  Is that the case?

Steve Berman