Bug#586373: libgtk2.0-0: huge performance decrease if Xorg's RENDER extension is disabled

Martin Monperrus martin.monperrus at gmail.com
Fri Jun 18 21:56:43 UTC 2010

Package: libgtk2.0-0
Version: 2.20.1-1
Severity: important

Dear Debian developers,

Because of a bug in a video driver, I had to disable Xorg's RENDER extension.
As a result, the performance of GTK decreased significantly, and the
applications on top of GTK, including Firefox and Eclipse, are almost

gtkperf with RENDER: 11s
gtkperf without RENDER: 40s

On the contrary, applications on top of QT perfectly resist disabling RENDER.


Additional information:
* It seems that GTK uses libxft when RENDER is present and libfreetype
* "pango-view --backend=ft2" is as slow as with RENDER disabled, the other
pango backends are always fast (with and without RENDER).
* I did not find in the documentation a way to configure libgtk so that it does
not use at all libfreetype as Pango backend.

-- System Information:
Debian Release: 5.0
  APT prefers testing
  APT policy: (990, 'testing')
Architecture: i386 (i686)

Kernel: Linux 2.6.28-15-generic (SMP w/2 CPU cores)
Locale: LANG=en_US.ISO-8859-1, LC_CTYPE=en_US.ISO-8859-1 (charmap=ISO-8859-1)
Shell: /bin/sh linked to /bin/bash

Versions of packages libgtk2.0-0 depends on:
ii  libatk1.0-0             1.30.0-1         The ATK accessibility toolkit
ii  libc6                   2.10.2-9         Embedded GNU C Library: Shared lib
ii  libcairo2               1.8.10-4         The Cairo 2D vector graphics libra
ii  libcups2                1.4.3-1          Common UNIX Printing System(tm) -
ii  libfontconfig1          2.8.0-2.1        generic font configuration library
ii  libfreetype6            2.3.11-1         FreeType 2 font engine, shared lib
ii  libglib2.0-0            2.24.0-1         The GLib library of C routines
ii  libgnutls26             2.8.3-3          the GNU TLS library - runtime libr
ii  libgssapi-krb5-2        1.8.1+dfsg-2     MIT Kerberos runtime libraries - k
ii  libgtk2.0-common        2.20.1-1         Common files for the GTK+ graphica
ii  libjasper1              1.900.1-5.1      The JasPer JPEG-2000 runtime libra
ii  libjpeg62               6b-16.1          The Independent JPEG Group's JPEG
ii  libpango1.0-0           1.28.0-1         Layout and rendering of internatio
ii  libpng12-0              1.2.43-1         PNG library - runtime
ii  libtiff4                3.8.2-11         Tag Image File Format (TIFF) libra
ii  libx11-6                2:1.3.3-3        X11 client-side library
ii  libxcomposite1          1:0.4.0-3        X11 Composite extension library
ii  libxcursor1             1:1.1.9-1        X cursor management library
ii  libxdamage1             1:1.1.1-4        X11 damaged region extension libra
ii  libxext6                2:1.1.1-3        X11 miscellaneous extension librar
ii  libxfixes3              1:4.0.3-2        X11 miscellaneous 'fixes' extensio
ii  libxi6                  2:1.3-4          X11 Input extension library
ii  libxinerama1            2:1.0.3-2        X11 Xinerama extension library
ii  libxrandr2              2:1.3.0-3        X11 RandR extension library
ii  libxrender1             1:0.9.5-2        X Rendering Extension client libra
ii  shared-mime-info        0.70-1           FreeDesktop.org shared MIME databa
ii  zlib1g                  1: compression library - runtime

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