I had a 6s for work, no way it can keep up with an XR. I was playing with one of the XR's here at work and it's no where close in speed. Emails alone in the outlook app load way faster.
Don’t know why you found that? I can place my phones side by side and their really isn’t that much different, the 6S with Touch ID unlocks faster too, also I find it’s much easier to double click the home button to bring your apps up, swiping half way to he screen isn’t very accurate.
And 3D Touch despite what anyone tells you is much easier to use then pressing on the keyboard spacebar hoping it works, because it’s not always reliable in activating your cursor, like when you want to edit posts on here. But hey is dead now which is a shame as it worked great.