So this lag is my opinion huh?Every. Single. Year.
It was the same in iOS 7 -> iOS 8 and it will be the same in iOS 9 -> iOS 10
That's your opinion.
In my opinion iOS 9 is better than iOS 8 since the beginning...
Your personal opinion
Here is visual evidence of Apple's crap optimisation for old devices and how even a budget Windows Phone beats it in that department.
Here is the horrible scroll stutter on my iPhone 6
And here is my Lumia 730 running the very same website silky smooth 60 fps and it cost me $120 (less than a quarter of my iPhone's price) around a year ago and it's wrecking my iPhone in smoothness.My Lumia has already been through 2 Windows versions and it's on Windows 10 in the video
And If someone wants I can Make a similar video with a Galaxy S6 which demolishes both of the above devices in scroll smoothness