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iOS 18 found to reduce performance on older iPhones to improve battery life

The iPhone 15 Pro may run slightly slower in some tasks after updating to iOS 18. (Image source: Swello - Unsplash)
The iPhone 15 Pro may run slightly slower in some tasks after updating to iOS 18. (Image source: Swello - Unsplash)
Apple finally publicly released the first stable version of iOS 18 earlier this week. While early adopters have encountered bugs like in previous years, it also turns out that Apple is making older iPhones slower to reduce power consumption in some tasks to maximise battery life.
Apple iPhone iOS

Apple published the first stable iOS 18 release a few days ago in time for the shipment of early iPhone 16, iPhone 16 Plus, iPhone 16 Pro and iPhone 16 Pro Max units. In short, the latest version of iOS retains compatibility with all iPhones as far back as the iPhone Xs. While iOS 18 brings various new features to the table, initial testing has also revealed that it may reduce performance across multiple iPhones.

It is worth noting that this is only true of iPhones that could previously run iOS 17. Hence, this excludes the new iPhone 16 series that cannot be downgraded before iOS 18.0. According to Geekerwan, he observed a 3.5% drop in single-threaded and multi-threaded performance between iOS 17 and iOS 18 when benchmarking the iPhone 14 Pro Max in Geekbench 6. Worse still, the newer iPhone 15 Pro Max (curr. $989 - renewed on Amazon) exhibits a 3.8% performance degradation in the same single-threaded benchmark, which extends to 3.9% in Geekbench's multi-threaded equivalent.

(Image source: Geekerwan)
(Image source: Geekerwan)

Although some variance exists in Geekbench's public database, the results obtained by Geekerwan are repeatable. While Geekbench does not reveal the reasoning behind the change itself, Geekerwan's own analysis suggests that Apple has tweaked the CPU boost clock behaviour in iOS 18 compared to its direct predecessor. As a result, it takes the A17 Pro approximately 33% longer to hit peak clock speeds in iOS 18 compared to iOS 17.

Consequently, this means that the likes of the iPhone 14 Pro Max and iPhone 15 Pro Max will be slower in synthetic benchmarks that run for a short period. However, the side effect, likely an intentional one, is to reduce power consumption. Theoretically, this should yield better battery life; however, the exact net increase remains to be seen in general usage for the time being.

(Image source: Geekerwan)
(Image source: Geekerwan)

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> Expert Reviews and News on Laptops, Smartphones and Tech Innovations > News > News Archive > Newsarchive 2024 09 > iOS 18 found to reduce performance on older iPhones to improve battery life
Alex Alderson, 2024-09-21 (Update: 2024-09-21)