If you’ve just updated your iPhone to iOS 27, you may have noticed faster battery drain and increased device heat during normal use. There’s no cause for panic. These effects are temporary and result from CPU-intensive background processes that occur after any major iOS update.

Apple warns that immediately after completing an update, especially a major release, users might experience a temporary impact on battery life and thermal performance. This is normal, as the device needs time to complete setup tasks in the background, including indexing data and files for search, downloading new assets, and updating apps. The impact of iOS 27 is more pronounced than usual due to the need to completely re-index the device for use with Siri AI, a process that may last several days.

Once all background processing finishes, the device will return to normal. In fact, the efficiency improvements in iOS 27 may lead to better battery life after the update completes its under-the-hood work.