Some users reported that replacing their old and well-worn battery with a new battery (OEM or third-party) restored overall system performance to a like-new state. It was surmised that Apple was throttling iPhones whose batteries capacities had fallen below a certain threshold in order to preserve battery life.
Primate Labs founder John Poole seems to agree with this “community” assessment after plotting the kernel density of Geekbench 4 scores running on iPhone 6s and iPhone 7 smartphones. The iPhone 6s is two years old at this point, while the iPhone 7 is a year old. That means that long-time users of these smartphones should have some pretty heavy charge/discharge cycles on their devices at this point, along with some battery degradation.
Poole's testing showed that large variances in Geekbench 4 scores began cropping up after iOS 10.2.1, which was a release that aimed to fix premature shutdowns on certain iPhone models. By the time iOS 11.2.0 rolled around, Apple's apparent CPU throttling algorithms really started ramping up, as we're seeing a multimodal distribution of scores.
"First, it appears the problem is widespread, and will only get worse as phones (and their batteries) continue to age," writes Poole. "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."
Whether intentional or not, Poole goes on to state that Apple's decision to approach battery performance with iPhones in this manner may leave customers with the wrong impression.
"While this state is created to mask a deficiency in battery power, users may believe that the slow down is due to CPU performance, instead of battery performance, which is triggering an Apple introduced CPU slow-down," Poole adds. "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'. This will likely feed into the “planned obsolescence” narrative.
As is usually par for the course, Apple has not released a statement regarding the latest uproar over iPhone battery performance degradation and processor throttling.