For almost as long as Apple has been issuing software updates for the iPhone, there have been complaints that new versions of iOS slow down older iPhones. This is supposedly so people are coerced into upgrading their devices. But there’s a logical explanation for this.
Apple has released a support document that explains what is actually happening. When a new operating system, like iOS 26, is installed to an iPhone a lot of changes take place aside from the superficial ones like Liquid Glass and new application features.
Here’s what Apple says:
Immediately after completing an update, particularly a major release, you might notice a temporary impact on battery life and thermal performance. This is normal, as your device needs time to complete the setup process in the background, including indexing data and files for search, downloading new assets, and updating apps.
For example, after significant system updates, the Spotlight index is rebuilt so searching is faster and more effective. And a bunch of other backend processes are replaced and updated. This can make your iPhone slower and hotter.
These processes can take several days as iOS prioritises what you’re doing over the backend processes that occur after a major update. Even if you’re not doing much with your iPhone, it may be working quite hard in the background. But your slow iPhone will recover in a few days and be back to running fast and cool.
Anthony is the founder of Australian Apple News. He is a long-time Apple user and former editor of Australian Macworld. He has contributed to many technology magazines and newspapers as well as appearing regularly on radio and occasionally on TV.