In your Xorg.0.log file there is an errors:
(EE) AIGLX error: dlopen of /usr/lib/dri/(null)_dri.so failed (/usr/lib/dri/(null)_dri.so: cannot open shared object file: No such file or directory) (EE) AIGLX: reverting to software rendering
In your Xorg.0.log file there is an errors:
(EE) AIGLX error: dlopen of /usr/lib/ dri/(null) _dri.so failed (/usr/lib/ dri/(null) _dri.so: cannot open shared object file: No such file or directory)
(EE) AIGLX: reverting to software rendering