Dear Maintainer,

I encountered a severe performance degradation after security updates
that I ran after several weeks without update.
Since the xserver-xorg seems the only package that might have such
consequence in the assumed timeframe, I'm reporting a bug here.

The 3D performance has never been on par with windows drivers for
such a powerful GPU, but it has been viable at least, with 20-40
FPS for the ordinary 3D games in low- to moderate details.
Now it is completely useless, most 3D games give 1 FPS or so.
Minetest gives 10, that is tragical for such a simple game.
The desktop and 2D games seem unaffected.

Interestingly, I tested on different machine with the old Intel
onboard GPU, and it works like before, unaffected.

It seems like 3D acceleration does not work at all now.
Maybe some odd driver (module) is being used for the Radeon GPU now?

The software environment is Debian 9 Sarge, LTSP thin client, games
are being executed as local apps on the client.
Only distributional graphic drivers are installed and the driver
(module) is selected and loaded automatically.