Editor's Note, 3:00 p.m. 12/20/17: This story has been updated with comment from Apple.
Apple is making some behind-the-scenes changes that impact its elder iPhones, according to Geekbench results, and, later, an official statement from the company. Recent updates try to balance a phone's CPU power draw with aging batteries, which slows the phone but allows for the same battery life you're used ot.
Geekbench developer John Poole evaluated a Reddit thread last week that suggested Apple's older iPhones, including the iPhone 6s and iPhone 7, weren't acting as responsively recently after software updates. And some of those users wondered whether, in a bid to boost battery life, Apple was throttling processor performance.
So, Poole used Geekbench's benchmarking testing to find out. He conducted single-core tests on iPhone 6s and iPhone 7 units running different versions of iOS. His findings suggest that Apple has made a tweak in iOS 10.2.1 to 11.2.0 that appears to throttle the iPhone's performance when the smartphone's "battery condition decreases past a certain point," Poole said.
The change was likely made after iPhone 6s users reported that their smartphones would spontaneously shut down even when there was seemingly more than enough life left on their batteries. Apple acknowledged the shutdown problem and offered a battery replacement program. The company also released an update to address it.
Poole pointed to one Reddit user, who goes by the handle "kadupse," who has the most likely explanation: "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 a statement to TechCrunch, Apple suggested that this is correct, but as a feature to prevent phones from shutting down when you need the most.
“Our goal is to deliver the best experience for customers, which includes overall performance and prolonging the life of their devices. Lithium-ion batteries become less capable of supplying peak current demands when in cold conditions, have a low battery charge or as they age over time, which can result in the device unexpectedly shutting down to protect its electronic components.
Last year we released a feature for iPhone 6, iPhone 6s and iPhone SE to smooth out the instantaneous peaks only when needed to prevent the device from unexpectedly shutting down during these conditions. We’ve now extended that feature to iPhone 7 with iOS 11.2, and plan to add support for other products in the future.”
Apple doesn't appear to be denying a performance hit. The operating system lowers peak performance and smooths them out over power cycles, which could, to some, make a phone seem slower, especially if its old or has a low charge.
It makes sense, to a degree: to keep your phone lasting longer, the CPU is throttled. But some users may see their phones slowing down
In other words, rather than just get a new battery, some iPhone users might feel compelled to get a new device when their phones shut down, and that obviously benefits Apple.