Ok, I dive in. The thing: for each kernel commit I should test I need to play
hours to see if the mini freezes happen... this will probably take a while.

The only significant change in my dota2 configuration from the configuration,
which seemed to work flawlessly, is that I play now in a 1920x1080 borderless
window with openbox window manager, instead of 2560x1600 fullscreen with mutter
window manager.

I'll try to locate a "good" commit from
26045b53c96f23b75a48544349c3d936e8402418