(In reply to fin4478 from comment #6)
> Comment on attachment 142770 [details]
> Xorg Log
> 
> Disable the Xfce compositor, vsync feature in that causes it tainted. That
> might not help.  Use the display port, development focus is in the display
> port. Developers have  display monitors and are not interested about hdmi so
> much.

That's it, I disabled V-Sync on Xfce compositor settings and there are no more
freezes or errors.
So this is a Xfwm4 bug?