Why my phone work slowly

@aryanraj could be an App issue. Make sure that you turn off all your apps that are running in the background. Also, turn off all push notifications as well. Start your phone in safe mode and see if that changes anything. To get there you need to

1. Press & hold the power button.

2. Press & hold the Power off.

3. Tap on Safe mode .

4. Safe mode enabled.

Check on here for more.

If none of that works, you may have to do a hard reset. Problem with that is that you are going to lose your pictures/contacts/music.etc. You will have to try to backup your phone first to avoid the loss of files. This shows how to do that.