How do I solve the lagging issue in iPhone 6s?

Only recently I have reset my phone and updated it with Ios10.3, with still 50GB of storage remaining. I always face lag, when and open or close a video in facebook app and also while dealing with any type of video posts, be it in instagram, snapchat or any such app…please give me solution for this

Clearing the RAM - Press and hold the power button until it displays “ slide to power off ” , then keep presssing the home button until that message disappears.
Hard reset- Try pressing both the home button and power button at the same time until the iPhone switches off. Keep holding till you see Apple logo. Try those apps which you felt were lagging before. If the problem is over then stop reading the steps written below.
Soft reset- Goto setting-> general->reset->reset all setting. If the problem is solved no need to read further.
Backup and restore - Sometimes due to insufficient space, your iCloud backup might be full to store all the images and apps stored in your iPhone. So just to be in the safe side, connect your iPhone to your laptop or pc. Do a full backup. Then restore your iPhone from that backup. Hopefully your problem is solved.