Firstly are you using iOS 10?If you are scroll down the list of notifications of 2 days in notifications centre.Swiping to the left of springboard has occasional stutter .Go in Settings-Mobile Data and scroll down the list of apps.There is stutter
You realize that iOS 10 is still in beta, right?
Yet you decided to buy the new iPhone due to the lag in the iOS 10 BETA?
You are one easy customer...