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 11.2.0 updates introduce this throttling for different devices. iOS 10.2.1 is particularly relevant, as this update was designed to reduce random shutdown issues for the iPhone 6 and iPhone 6S. Apple’s fix appears to be throttling the CPU to prevent the phone from randomly shutting down. Geekbench reports that iOS 11.2.0 introduces similar throttling for low iPhone 7 low capacity batteries.
Some Reddit users report that replacing their batteries has returned performance and CPU clock speeds back to normal. The reports are particularly troubling because any perceived slowdowns by iPhone users might tempt owners to upgrade their entire device instead of replace the battery. “This fix will also cause users to think, 'my phone is slow so I should replace it' not, 'my phone is slow so I should replace its battery,’” says Geekbench’s John Poole.
Source: https://www.theverge.com/2017/12/20/16800058/apple-iphone-slow-fix-battery-life-capacity
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 11.2.0 updates introduce this throttling for different devices. iOS 10.2.1 is particularly relevant, as this update was designed to reduce random shutdown issues for the iPhone 6 and iPhone 6S. Apple’s fix appears to be throttling the CPU to prevent the phone from randomly shutting down. Geekbench reports that iOS 11.2.0 introduces similar throttling for low iPhone 7 low capacity batteries.
Some Reddit users report that replacing their batteries has returned performance and CPU clock speeds back to normal. The reports are particularly troubling because any perceived slowdowns by iPhone users might tempt owners to upgrade their entire device instead of replace the battery. “This fix will also cause users to think, 'my phone is slow so I should replace it' not, 'my phone is slow so I should replace its battery,’” says Geekbench’s John Poole.
Source: https://www.theverge.com/2017/12/20/16800058/apple-iphone-slow-fix-battery-life-capacity
. should i go ahead or not .upgrading from iphone 5s
Although, very very rarely, the device restarts for no obvious reasons. But then since it isn't often, I am least bothered. 