100% cpu with every scroll in LibreOffice

Internal full HD display here, also got only slightly better.

There is a (temporary) fix: use “SAL_USE_VCLPLUGIN=gen libreoffice” to start libreoffice (make sure that no other libreoffice-process is already running). Then, libreoffice looks ugly but works without increased cpu usage of xorg.

To add more information: I do have the exact same problem in Debian 11 (Libreoffice 7.1.x) as well as Fedora 34 (Libreoffice 7.2.x): xorg cpu usage goes up to 100% if any action is done within libreoffice in Qubes 4.1.

Special case: open an empty libreoffice-calc document. Select any empty cell: everything runs smooth. Input a simple formula (i.e. “=1+2”) in a cell. Selecting this very cell has a lag and 100% cpu usage in the xorg process do occur.

This behaviour started some weeks ago and was not the case about 2 months ago, even in qubes 4.1. So some update has to be the culprit. Unfortunately, I do not have any good solution other than setting the ugly generic VCLPLUGIN.


Looks like it worked!
So it set an environment variable to the value “gen libreoffice”?.. Just curious what it does.

It runs libreoffice with the SAL_USE_VCLPLUGIN environment variable set to value gen. Apparently this tells the libreoffice Visual Class Library to select a plugin named gen (as opposed to, say, gtk3 or qt5). It is likely that the Gtk plugin wants to use OpenGL, which ends up being software-rendered.

I thought maybe instead of switching off Gtk we can disable the attempt to use OpenGL, eg. with GDK_DEBUG=nogl instead. But a quick test (20 pages of lorem ipsum) does not show any difference in a Debian 10 qube (even with SAL_USE_VCLPLUGIN=gen)

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Sorry to horn in but, have you checked into this libreoffice variable then (SAL_NOOPENGL)? Just to see what it changes. I see that this was used by the previous incarnation of libreoffice (openoffice) but perhaps it didn’t make the cut when they switched names.


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Yep, unfortunately “GDK_DEBUG=nogl” does not help. Disabling hardware-acceleration and/or anti-aliasing in the options menus does not help either like SAL_NOOPENGL. The only fix seems to be “SAL_USE_VCLPLUGIN=gen”

FYI: if you uninstall the package “libreoffice-gtk3” in your template VM, you basically have the same effect as “SAL_USE_VCLPLUGIN=gen libreoffice” in every AppVM.