When the Android phone is turned on, it sometimes prompts "Android is starting and optimizing the nth application (***N)".

Android phone display is optimized: the optimized display is usually when the phone is turned on and the system is updated and enters the desktop for the first time. This is a normal phenomenon. After the optimization is completed, it will automatically enter the desktop. In case of special circumstances, the optimization can not be completed, mostly because the update failed. You can go to rec to reinstall the update package and try again after restarting your phone.