As an avid Apple user, I run an iPhone, iPad and MacBook Pro as part of my daily workflow. It always seems widely reported with every new iteration of the operating system, especially for mobile devices, that battery life suffers. In a sense this makes perfect sense, new features are added with every major iOS release milestone and these are aimed at the latest hardware and so cause performance degradation on older supported iOS devices as the new features aren’t always aimed at the hardware of older devices.
However, after upgrading to iOS 11 after much hesitation, I noticed that on my iPhone 6s that the battery life suffered from it’s usual 10% per hour usage to closer to 20% per hour. The bigger issue seemed to be performance, opening apps, taking photos and doing usual everyday tasks took seconds longer than usual. I didn’t feel that the iOS 11 update should cause such a huge performance degradation on a 2 year old device, so I looked into Geekbench results and found similar issues to those pointed out by John Poole. The following Geekbench results are from the same iPhone 6s, about 2 years apart.
As you can see there is a 1072 score drop in single core and 2019 score drop in multi core results for the same device. The reason for this, according to other reports, is that Apple is throttling the CPU cores within the iPhone due to battery life degradation. This is the results of a device at 74% of it’s original battery capacity and 517 cycle counts. Due to the throttling introduced by Apple, the performance of a £630 device has halved in the space of a year as this device was already replaced due to the random shutdown issue. In order to fix the performance degradation introduced by Apple it costs the user £79 to get the battery replaced by Apple directly, which seems unreasonable for a device that was only manufactured a year ago.
Update: Apple has responded to the issue by offering an iOS update in early 2018 that will offer users more visibility into battery life and see how it’s affecting performance. Apple has also lowered the price of out-of-warranty battery replacement for iPhone to $29/£25 respectively for anyone with an iPhone 6 onwards.