1) Too many apps running in the background or if the system cache has not been cleared may cause your device's system to lag. Touch the Menu key in the bottom corner of screen to view recently used applications, touch “Clear all”.
2) Uninstall unused apps from time to time to ensure that your device has sufficient storage space.
3) Charge your device until the battery level is at least 30%.
4) Try to restart your device.
5) If the issue occurs while using a third-party app, please uninstall the third-party app.
6) If you are playing games, watching online videos or listening to online music, your device may lag or freeze because of a poor network connection. Enable Aeroplane mode for a few minutes, then disable it and check your network connection again. Alternatively, move to a location with a better network connection.
7) Please back up your personal data, then reset or update your device to the latest system version.