If you have an older iPhone that you bought 2+ years ago you might suddenly start to notice a slowdown.
You may start to think Apple are pushing software updates made to deliberately slow down your iPhone to encourage you to upgrade to a new one. But this is false.
Over time, just like laptop batteries, iPhone batteries degrade, giving less and less battery life and making the phone less reliable. Some power for the CPU comes from the battery, but if the CPU requests for more power than the battery’s got, it can trigger a sudden shutdown.
Just imagine if these kept happening. How unbearable it would be. You may even start carrying around a non-iPhone as well to use in the case your iPhone unexpectedly shuts down.
If your capacity is above 80%, there isn’t really much to worry about, but if it’s under 75%, you might want to start looking at a battery or phone replacement.
Apple’s answer to this comes in the form of performance management. Simply, when your iPhone detects that it is booting back up from an unexpected shutdown, it starts to limit the CPU’s performance to prevent the shutdown happening again. This is why your iPhone will become slower after an unexpected shutdown.
You can turn off performance management either by replacing the battery of your iPhone, or heading to Settings –> Battery –> Battery Health, where an option to disable it should be present provided your iPhone is running iOS 11.3 or later. You can also see your battery health percentage here. Please be aware that if an unexpected shutdown occurs again it will be enabled again.
iPhone 3G, 4, and 4S slowdowns
Despite what me saying above was true for most iPhones, it appears that the last major OS upgrades for these devices slowed them down and made them unusable in some cases.
The iPhone 3G received iOS 4 but did not receive many of the iOS 4 features such as wallpapers and multitasking and iOS 4 made existing functionality a lot slower on the iPhone 3G. This was not due to battery degradation but rather due to planned obsolesence. Apparently, some of the issues were fixed on iOS 4.x updates, however.
The iPhone 4 received iOS 7 and missed out on a few features but still had a lot of the functionality. However, in some cases iOS 7 would lag on this device especially when browsing the internet and switching between apps.
The iPhone 4S received iOS 9 and missed out on a few features but still had a lot of the functionality. However, it was unusable. It would lag everywhere. This led to me downgrading my 4S to iOS 8.4.1 by downgrading to 6.1.3 through the signed IPSW and then installing the 8.4.1 OTA.
These are only three cases however and I doubt Apple are planning on deliberately slowing down any more iPhones now that word is out about those three.
So if your iPhone has become slower, unless you’re on a 3G, 4, or 4S, blame your battery, not Apple. They only want to ensure that your phone is reliable and doesn’t unexpectedly shut down.
What’s your experience with the performance management feature? Tell me below in the comments!