Try to disable unused applications that start when you boot the system I did it and for me it worked .
Disable some startup applications
By default on Ubuntu startup applications are no longer visible, for "security reasons" for new users, those processes that are started at boot time, some may be turned off if you do not need them, speeding up the boot, for make them appear open the terminal and type:
cd / etc / xdg / autostart /
sudo sed - in-place 's / nodisplay = true / nodisplay = false / g' *. desktop
Then insert our password. Applications now open boot and disable the services that you do not need