Why it is running so slow? There could be a few reasons below,
*Unclear App Cache.
*Enable So many Widgets.
*Hevvy load of internal storage.
*Unknown virus.
*Havvy Loaded apps.
*And many others reasons.
To Solve This Problem, Follow the step.
*Open your device's Settings app .
*Tap Apps & notifications.
*Tap See all apps the app Storage.
*Tap Clear data or Clear cache. (If you don't see "Clear data," tap Manage space.)