do a clean flash of iOS it will solve the issue. Most issues with iOS comes because of upgrading from one version to the next version. i always completely flash my iPhone when i go to the Next iOS Version. im using DFU mode instead of Recovery Mode and then instead of upgrade i choose Restore. Be aware that it will delete everything on the Phone
From your two posts it seems you aren't familiar with the issue. Rest assured many things have been tried already including restoring with little success.the shown is not a lag. it is that the way the user swipes on first half it wants to go to the recent app screen but because he swipes up more it goes to home screen
The video in that post does show the lag and it's just a normal swipe. I know it's hard to tell from a screen recording.