About a week ago, a massively popular and widely circulated thread on Reddit posited that Apple purposely slows down performance on iPhones with older batteries. The basis for the seemingly sensational claim stemmed from a user who replaced his iPhone 6s battery with a brand new one and quickly noticed that performance was much improved. After doing some Geekbench testing with both the older battery and the new one, his suspicions were backed up by cold hard data.

Diving into the matter, Geekbench founder John Poole recently decided to do some testing of his own by measuring system performance on the iPhone 6s and iPhone 7 running various iterations of iOS. Poole subsequently found some interesting performance degradation when going from iOS 10.2.0 and 10.2.1.

So what exactly is going on here? Is it possible that all the cynics who have been claiming that Apple engages in planned obsolescence have been right all along? That’s something of a stretch, but the reality is that Apple has been limiting performance on certain iPhone models with older and lower-capacity batteries as a means to prevent unexpected shutdowns via sudden battery drainage.

First, it appears the problem is widespread, and will only get worse as phones (and their batteries) continue to age. See, for example, the difference between the distribution of iPhone 6s scores between 10.2.1 and 11.2.0.

Second, the problem is due, in part, to a change in iOS. The difference between 10.2.0 and 10.2.1 is too abrupt to be just a function of battery condition. I believe (as do others) that Apple introduced a change to limit performance when battery condition decreases past a certain point.

Shedding some further light on the matter, Poole cites the following explanation that appeared on Reddit:

Because degraded batteries last much less and end up with a lower voltage Apple’s solution was to scale down CPU performance, it doesn’t solve anything and is a bad experience… but it’s better than having your device shutdown at 40% when you need it the most.

In short, Apple is apparently curtailing system performance in the interest of improved battery life. The end result, though, is that most users will be under the impression that their phone is slowing down and that it may be time to upgrade.