Apple confirms iPhones with older batteries will take hits in performance

Reddit users have noticed that Apple appears to be slowing down old iPhones that have low-capacity batteries. While many iPhone users have experienced perceived slowdowns due to iOS updates over the years, it appears that there’s now proof Apple is throttling processor speeds when a battery capacity deteriorates over time.
Geekbench developer John Poole has mapped out performance for the iPhone 6S and iPhone 7 over time, and has come to the conclusion that Apple’s iOS 10.2.1 and 11.2