Symptoms: mame [arcade emulator] & fceu [nes emulator] are too slow to be used. surprisingly zsnes [snes emulator] & videos on the internet work finely.
I doubt the problem is related to severe looking complaints on dmesg about the integrated Radeon GPU
Here's the dmesg output about GPU & Radeon:
I think everything worked with the previous version of Debian, but in the current version this has been the problem. I wonder if some driver has changed in the update.