I've upgraded a number of machines to Ubuntu 16.04, which brought in KDE/Plasma 5.5.5. In some of our environments OpenGL is not working or is slow. For example, on some machines that have the main display connected to the on-board graphics card and have an Nvidia GPU for CUDA computing, GL is broken at the moment because the NVIDIA packages. Also, we have an NX server that allows users run KDE desktop remotely, which technically supports OpenGL, but it's a big slowdown, so it would make sense to give OpenGL up when it's only used for eye candy.

Is it possible to run KDE/Plasma 5 with OpenGL completely disabled?

Ideally, I would like a system-wide configuration to turn this off, since we are a multi-user environment, but any pointers would be appreciated.

Thanks!

Is it possible to run KDE/Plasma 5 with OpenGL completely disabled?

You could try to change the rendering backend to the XRender at the KDE System Settings > Display and Monitor > Compositor.



Another option is to disable the compositing - setting 'Enable compositor on startup'. The shortcut 'Alt + Shift + F12' will disable/enable the compositing on session.

There are few bug reports:
- Bug 371671 - Panel won't auto-hide after enabling/disabling compositing : https://bugs.kde.org/show_bug.cgi?id=371671
- Bug 353983 - Turning off compositing breaks Plasma panel rendering : https://bugs.kde.org/show_bug.cgi?id=353983

I would like a system-wide configuration to turn this off,

The backend setting and the compositing setting are saved to the $HOME/.config/kwinrc. You could try to set the system wide default. Same way as this: Set system wide default lock screen background image - viewtopic.php?f=289&t=141475 .

Note !
I have not tried the '/usr/share/my-settings/kwinrc' so I can't say if it will work.