People upgrading to iOS 13 this year may have more of an incentive than usual to keep using their old phones rather than upgrading to new ones. After all, 2016's iPhone SE was the last Apple phone to include a 4-inch screen suitable for smaller hands and pockets, and both the SE and the 6S were Apple’s last phones to include conventional 3.5mm headphone jacks.

But running Apple’s newest software on its oldest supported hardware hasn’t always been a pleasant experience, something we’ve been tracking going all the way back to iOS 6 and the iPhone 3GS in 2012 (see also: iOS 7 and 7.1 on the iPhone 4; iOS 8 and 9 on the iPhone 4S; iOS 10 on the iPhone 5 and 5C; and iOS 11 and 12 on the iPhone 5S). After using iOS 13 on both the 6S and SE recently, I can say that both devices still feel just fine to use—if you’re happy with how iOS 12 runs right now, you’ll be fine with iOS 13, too. They’re both good for hand-me-down devices. But there are still compelling reasons to upgrade if you’re thinking about it, and good reasons not to buy a used or refurbished version of either phone just to get the small screen or the headphone jack.

Apple’s A9 is still pretty good

For this performance test, I did a fresh install of iOS on each device, signed it into a test iCloud account, and let the phones sit for a while to complete any indexing or other behind-the-scenes tasks. I then opened each app three times and averaged the results. In the past, this has been a fairly reliable indicator of how each phone will actually feel in day-to-day use. If opening an app and waiting for it to load on a fresh iOS install feels slow, that usually means that the rest of the phone (including waiting for the keyboard to pop up, waiting for pages to load, and other tasks) will feel slow too, especially as you download more stuff and connect more accounts.

In general, iOS 13 running on these phones is almost imperceptibly slower than the same phones running iOS 12, though in many cases performance breaks just about even. If some of the percentages seem high, it's because the times are so low that any difference at all looks like a bigger deal than it is—in practice, you don't really feel any of these differences. The only outlier is the TV app, which did take significantly longer to fully load in iOS 13 than in iOS 12, but we're just talking about a small delay in an app that people aren't going to use as often as Messages or Mail.

iPhone 6S performance Application iOS 12.4.1 iOS 13.0 GM Difference (%) Safari 0.69 seconds 0.95 seconds +37.7% Camera 1.09 seconds 1.15 seconds +5.5% Settings 0.60 seconds 0.61 seconds +1.6% Mail 0.75 seconds 0.77 seconds +2.7% Messages 0.62 seconds 0.67 seconds +8.06% Calendar 0.50 seconds 0.59 seconds +18.0% Maps 1.29 seconds 1.53 seconds +18.6% Notes 0.86 seconds 0.80 seconds -7.0% TV app 1.84 seconds 2.88 seconds +56.5% Cold boot 13.10 seconds 12.98 seconds -0.9%

iPhone SE performance Application iOS 12.4.1 iOS 13.0 GM Difference (%) Safari 0.67 seconds 0.83 seconds +23.9% Camera 1.18 seconds 1.02 seconds -13.6% Settings 0.61 seconds 0.65 seconds +6.6% Mail 0.70 seconds 0.93 seconds +32.9% Messages 0.60 seconds 0.68 seconds +13.3% Calendar 0.56 seconds 0.64 seconds +14.3% Maps 1.35 seconds 1.38 seconds +2.2% Notes 0.92 seconds 0.79 seconds -14.1% TV app 1.96 seconds 2.58 seconds +31.6% Cold boot 14.01 seconds 12.87 seconds -8.1%

One reason why iOS 13’s performance isn’t a problem on the oldest phones that run it is because Apple has dropped support for multiple iPhone generations this time around: 2013’s iPhone 5S and 2014’s iPhone 6 and 6 Plus are all gone. Apple is still supporting the A8 processor from the 6 and 6 Plus elsewhere in its ecosystem—the iPad Air 2 and Mini 4, the 4th generation Apple TV, and the HomePod all run some version of the A8 and will all run some version of iOS 13—but those supported devices all include 2GB of RAM instead of 1GB.

It should be no surprise that the A9 can run iOS 13 well. In benchmarks, it’s almost twice as fast as the A8, and this chip was already the cutoff point for some new features that Apple has introduced in the last couple of years, including all of its augmented reality features and hardware decoding support for the HEIF and HEVC image and video formats Apple started using a couple of years ago. Newer chips are unquestionably faster and more power-efficient (the A9 was Apple’s last processor without a mix of large high-performance CPU cores and small power-saving cores), but in terms of raw performance and hardware features it’s still a fairly modern processor.

Regardless of the difference between iOS 12 and iOS 13 running on the same hardware, iOS 13 running on the 6S and SE still feels faster than running iOS 12 on the iPhone 5S or iPhone 6, and both of those phones were perfectly usable when I tested them last. Several apps open in just over half a second, which is essentially instantaneous. The only apps you’ll wait on, compared to a faster phone like the iPhone XR, are ones like Maps and TV and the App Store. These are heavier apps that need to load more things before they start responding to user input.

Older hardware with older designs

The larger issue for both of these phones, even if you didn’t buy them back in 2015 when they were new, will be physical wear and degradation of the batteries. The 6S I used to test iOS 13 ran the operating system perfectly well, but even with a brand-new battery directly from Apple, I could never make it through a whole day without needing to recharge. The 6S and 6S Plus had slightly worse battery life than the iPhone 6-series they replaced or the iPhone 7-series that replaced them, and today it’s the most noticeable thing about using the phones. After almost a year with my iPhone XR, which can last a full day and a sleepless-infant-filled night before it needs to be plugged in, the 6S feels even worse. And Apple has made iPhone XR-esque battery life a major selling point for both the iPhone 11 and the 11 Pro.

For the SE, which has always fared better in the battery department, the screen size is more pressing. For people still hanging on to the SE, the small size and the small screen might be the entire point, but there are more areas creeping into the operating system where Apple is just shrinking things down to fit the display, rather than keeping text, buttons, and images the same absolute size as they are on larger phones and just fitting less stuff onscreen at once.

Andrew Cunningham

Andrew Cunningham

Andrew Cunningham

Andrew Cunningham

Take the widgets that appear alongside the context menus when you long-press some icons on your home screen as an example. When these were originally designed, they were intended for the 4.7- and 5.5-inch screens of the iPhone 6S and 6S Plus, since they only appeared on phones with 3D Touch (an experiment that Apple is happily giving up on, since it was never really made clear why a long press couldn't do all the same stuff). But now that they're accessible on a smaller screen, rather than keeping the contents of the widget the same size and tweaking the size of the box, the box and all of the stuff inside it are just smaller, harder-to-read versions of what you'll see on larger phones.

I do fully appreciate the plight of the small-handed and small-pocketed who have had to watch phone sizes steadily and inexorably increase over the last decade. I also don't think that the areas where the SE's size affects its utility are things that most people are really going to be bothered by. It's just feeling awfully cramped these days.

All of that said, iOS 13 is still a good update on these devices. Having those 3D Touch features available on phones without the 3D Touch hardware is a welcome and long-overdue change, and Dark Mode looks excellent, especially on phones with a black bezel. The main reason to buy a new phone is because you want a larger screen, Face ID, or better battery life, not because your current phone feels slow or is missing features. If you’re worried about early bugs, I don’t think it’s a bad idea to wait for the iOS 13.1 update at the end of the month, but otherwise this new software isn’t going to make your phone suddenly feel even older than it is.