'iPhone slow': The truth about iOS updates

stack of old iphones
stack of old iphones (Image credit: iMore)

Every year "iPhone Slow" makes headlines. So what's really going on with iOS updates and iPhone performance?{.intro}

Update: As of iOS 10.2.1, Apple has begun prioritizing battery life over performance, which will slow down older iPhones.

In late 2016, Apple made a change that brought battery life into the iOS advanced power management system. Previously, if a battery was old, cold, or experiencing power spikes, it could drain or shut off unexpectedly. To prevent that, Apple began ramping down the processor, similar to how almost all processors have almost always been ramped down to control heat.

"Our goal is to deliver the best experience for customers, which includes overall performance and prolonging the life of their devices", Apple told iMore. "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."

More information on why Apple slows down old iPhones to save your battery.


Last week, a story went viral that claimed Apple was intentionally slowing down older iPhones to push people to buy its latest models.The claim was based on data which shows Google searches for "iPhone slow" spiking dramatically with the release of each new model.

That's been happening for years — I wrote about it in 2014:

Since Apple is updating almost everyone at the same time, searches will all be performed around the same time. Since Samsung and other Android manufacturers are updating only a few at a time and at different times, searches will be spread out across a very, very wide range of times.

Apple has a performance team tasked with making sure older devices don't slow down. Many engineers and others in the company carry older devices specifically to test for issues. And almost everyone has parents, siblings, kids, and other family members and friends on older devices. As a company, Apple does everything it can to ensure all supported devices run iOS as best as they can.

FutureMark went on to test raw processor performance of a range of iOS 11-supported devices:

We looked at data for the iPhone 5s first because, if older devices are being deliberately slowed, the effect should be most obvious with models that have been around for longer.The chart below shows iPhone 5s GPU performance over time. Each bar shows the average 3DMark Sling Shot Extreme Graphics test score calculated from all results submitted during that month. A higher score indicated better performance. The bars are coloured according to iOS version.As you can see, iPhone 5s GPU performance has remained consistent from iOS 9 to iOS 11 with only minor variations that fall well within normal levels.

What this shows is that Apple doesn't artificially slow down processors on older iPhones. It doesn't show how well Apple or app developers optimize code for those processors.

So, while it's great FutureMark is helping to dispell the dumbest of the dumb stories, there's still a lot of work Apple can do to improve things like frame-rate and interaction speeds on older devices. That's typically what happens in the point releases. (No amount of internal testing can come close to the data and insight you get from millions of people suddenly hitting the new version.)

Clean installs can help with that as well. I still install clean every year, even though it's a pain in the apps, and I still feel like I get better performance because of it.

Either way, "iPhone slow" simply isn't a thing, even if every year, every forum and click-site tries its best to make it into one. So, if you ever hear a friend or family members asking about it, explain it to them. And if they need help troubleshooting specific issues, just send them iMore's way.

Rene Ritchie

Rene Ritchie is one of the most respected Apple analysts in the business, reaching a combined audience of over 40 million readers a month. His YouTube channel, Vector, has over 90 thousand subscribers and 14 million views and his podcasts, including Debug, have been downloaded over 20 million times. He also regularly co-hosts MacBreak Weekly for the TWiT network and co-hosted CES Live! and Talk Mobile. Based in Montreal, Rene is a former director of product marketing, web developer, and graphic designer. He's authored several books and appeared on numerous television and radio segments to discuss Apple and the technology industry. When not working, he likes to cook, grapple, and spend time with his friends and family.