Do those devices include the 6s Plus? Not all the devices run the same and this video shows the lag and frame dropping pretty clearly. Maybe before you make a post like the one treating lag like a rare thing, you should think about more than just your own devices. I'm sorry if "smoking gun" is too much of an exaggeration when this is the most expensive iPhone that can be purchased and Apple has promised 1.6x improvements in performance. It's not excusable at all.
6+ and Air 2. Running fine.
What will a video prove? You'll see something you don't like, that doesn't bother me in the least. I've never said I didn't have minor animation issues, but I also don't spend my time discounting those who say they don't have any lag. Sound familiar?
If my iPhone or iPad works with a minor animation issue here or there and if it doesn't hinder my usage, I'm perfectly fine. I don't have time to spend on the little things in life and to me, this is a little thing. It's insignificant in the grand scheme of running iOS 9 and getting the stable results that make me happy.
In other words, I don't base my entire experience on fluidity issues. I report those issues, like I report every other issue and hope they address them. That's all I can do my man.