how iphone works
One of my longtime pet projects has been tracking the performance of new iOS versions on the slowest hardware that can run it. I was pleasantly surprised by the iPhone 3GS and iOS 6, but after that I was in for several years of disappointments. And now we come to iOS 11 and the iPhone 5S. Apple's transition to all-64-bit hardware and software, begun just four short years ago, has now completed, and the newest iPhones are easily four or five times faster.

Does the iOS 11 update leave the original gold iPhone feeling shiny and new, or does it come away feeling tarnished, Every time a new iPhone is released, it does some stuff that previous iPhones couldn’t do. Sometimes that just means going faster, and sometimes that means the addition of special hardware like a fingerprint sensor or NFC chip.

Here’s a combination of all the hardware and software features the iPhone 5S is missing relative to the iPhone 7, not including processor benchmarks or camera improvements. You can't use the LTE version of the Apple Watch Series 3 with an iPhone 5S; the LTE requires an iPhone 6 or newer. The non-LTE version of the Series 3 (and all other watchOS 4 hardware) works just fine.

That's not a small list, but unlike past years, it's relatively light on core features, and most of what's missing is enabled by extra hardware the 5S just doesn't have rather than speed. Some of the iOS 11 apps don't fare too badly, in absolute terms. But there are some fairly significant regressions, particularly in Mail, Notes, and Maps; and boot time goes way up (though totally rebooting your phone is not something you're actually going to do all that often).

These are, in the scheme of things, small differences, but seconds and fractions of seconds spent waiting on a phone over its lifetime do add up. The phone's single gigabyte of RAM is also starting to feel seriously restrictive, particularly in Safari, where tab reloading is a common phenomenon once you have more than two or three tabs in memory at a time.

Speaking strictly in qualitative terms, using iOS 11 on an iPhone 5S doesn't feel bad. You notice the impact of background tasks more than you used to—updating apps or downloading a bunch of music in the background makes the whole phone feel sluggish. Safari performance improves marginally in common benchmarks, though in the heavier JetStream benchmark it regresses just a bit. Don't expect rendering speeds to improve much overall.

If you want to speed general performance up a little, you may actually have some luck enabling the Reduce Motion option in the Accessibility settings. It often shaves around a quarter-second or so from the longer app launch times—apps that take around a second to launch don't benefit, but apps that take two or three seconds to load normally do. 79 (still a small fraction of the price of a new iPhone, even an iPhone SE).

But as I do every year, for most people I would come down in favor of updating. The iPhone 5S is slower with iOS 11, sure, but it's not as slow as the iPhone 4S was with iOS 8 or 9, or even as slow as the iPhone 5 is with iOS 10 most of the time.

And as we mentioned, you still get a bunch of new iOS 11 features, and you're bound to find something worth upgrading for in that list. Even more importantly, though, you need to be on iOS 11 to get new security updates at this point. So, update. If not today, then soon.



The iPhone 5S gets a little slower, but that's how it goes when the oldest hardware that runs an operating system is only 20 or 25 percent as fast as the most recent hardware. It'll never be as fast as it was, but it's fast enough for a budget or hand-me-down phone, and it keeps doing new things; that's an acceptable trade-off.