After playing my new Mini4 alongside the Mini3 for a week, both set up the same (the 4 is a restore copy of the 3), I am really leaning toward a combo of poor programming / lack of quality testing in iOS9 and planned obsolescence. The Mini3 isn't bad, but it runs so poorly compared to the Mini4 executing the same tasks. Significantly worse than the 6+/6S+ comparison.
By itself the Mini3 isn't bad. However when you do a side by side it is worse than the hardware would suggest.
By itself the Mini3 isn't bad. However when you do a side by side it is worse than the hardware would suggest.