We weren't impressed by iOS 7 on the iPhone 4. The Apple A4 that powers the phone is now nearly four years old, and you can feel it from the moment you turn the phone on. It just isn't well-suited to iOS 7's big, sweeping animations and other graphical effects, and its jerky performance is worlds away from what you'd get on a new iPhone 5S, 5C, or even the one-year-newer 4S.

iOS 7.1 is the new operating system's first major update. While there's only so much Apple can do to optimize its software for old hardware, we hoped it would improve the iPhone 4's performance enough to make things pleasant for people squeezing another year out of their phones.

What doesn’t change

iOS 7.1 doesn't perform any differently in CPU, GPU, or browser-based benchmarks than iOS 7.0. Apple sometimes takes these medium-sized updates as an opportunity to further optimize Mobile Safari's JavaScript engine, but that's not the case here.

You're also missing the same iOS 7 features that you didn't get in the 7.0 release, a list which we'll reprint here for your convenience alongside all of the iOS 5 and iOS 6 features the iPhone 4 didn't get.

3D Flyover or turn-by-turn navigation in Maps

Panorama mode or Filters in the Camera app (filters can still be applied after the fact in the Photos app)

AirPlay Mirroring

Siri

AirDrop

A number of the new graphical effects present on all other iOS 7 devices. These include translucency effects throughout the OS, live wallpapers, and the parallax effect used on the Home screen

Aside from these items, the general UI tweaks introduced by iOS 7.1 are all present on the iPhone 4—we'll go into more detail in our full review (coming soon).

Performance

Luckily, there are plenty of things Apple can do to speed up iOS 7.1 that won't show up in benchmarks. The worst speed-sapping problem that afflicted iOS 7 was its flashy, overlong UI animations, which were sometimes used to cover up application load times but more often added unnecessary seconds to the amount of time it took to do anything. This was true whether you were using an old iPhone 4 or a brand-new iPhone 5S freshly liberated from its packaging. These animations could sometimes double the amount of time it took to launch common apps on the iPhone 4 compared to iOS 6.1.3 running on the same hardware. Even worse, you usually had to wait for these animations to complete before you could do anything else, which sometimes made iOS 7 feel less responsive than previous versions had been.

iOS 7.0.3 was a first step toward fixing this problem for people who knew which settings to tweak. Going into the Accessibility Options and toggling "reduce motion" originally just disabled the parallax effect used on the home screen and throughout the operating system, but version 7.0.3 also disabled the sweeping animations used to transition from app to app. In its place was a crossfade effect that was less flashy but also demonstrably faster.

iOS 7.1 solves the problem for people who don't tweak their devices' settings or for people who like the way the animations look but not how they feel. Animation durations have been shortened noticeably throughout iOS 7.1, and toggling "reduce motion" is now purely cosmetic. To show how this speeds up even the slowest of Apple's phones, we re-ran our application launch tests under iOS 7.1 and compared them to the results from iOS 6.1.3 and 7.0.

The numbers below measure the time between when the app icon is tapped and when the app becomes ready for user input. Each app's launch time was measured three times and averaged. The apps were force-quit using the iOS multitasking interface between runs.

Application iOS 6.1.3 iOS 7.0 iOS 7.1 GM Safari 1.13 seconds 2.05 seconds 1.8 seconds Camera 1.9 seconds 2.63 seconds 2.2 seconds Settings 1.31 seconds 1.88 seconds 1.37 seconds Mail 1.0 seconds 1.50 seconds 1.35 seconds Messages 1.57 seconds 2.80 seconds 1.5 seconds Calendar 1.23 seconds 1.78 seconds 1.37 seconds Phone 0.67 seconds 2.37 seconds 1.83 seconds Cold boot to lock screen 31.14 seconds 45.13 seconds 43.1 seconds

There's a measurable improvement over iOS 7.0 across all of these apps, some more noticeable than others. In a few instances, iOS 7.1 very nearly catches up with iOS 6.1.3, which is impressive given the gap between the two operating systems in some of these apps. It's not a complete recovery from the original iOS 7.0 release, but it's about as good as Apple can do with hardware this old. The small speed improvements are present throughout the operating system, and this makes the iPhone 4 feel more responsive than it did, if not always as responsive as it once was.

iOS 7.1 also helps with the UI jerkiness that was all over the place in 7.0. It's easiest to capture the difference in video—actions like launching apps or pulling up the Control Center shade are always visibly jerky in iOS 7.0, but they're smooth (or at least smoother) in the new update.

iOS 7.1 makes the iPhone 4 visibly faster and smoother. Music credit: "Show Your Moves" by Kevin MacLeod.

None of this is to say that jerkiness is entirely banished from the iPhone 4—all you have to do is open the Settings app and scroll around to see how true that is (try scrolling through the wallpaper selection to see it at its worst). The situation is much better, though, and much of the stuttering and jerkiness that's left was also present in iOS 6. You can't expect Apple to magically circumvent the limitations of old hardware, but at the very least it can try to avoid making things worse.

As good as it gets

iOS 7.1 will almost certainly be the last major software update the iPhone 4 ever receives. No iOS release has progressed beyond version X.1 since iOS 4.3 was released back in March of 2011. There might be minor features and tweaks added in smaller updates between now and the launch of iOS 8, but these almost never have significant impacts on performance.

iOS 7 is unlikely to run better on the iPhone 4 than it does in iOS 7.1. That's not to say that the experience is great—even stepping up to an iPhone 4S would get you noticeable gains in performance and overall smoothness—but it's better than it was, and it's as good as it's going to get.

If you're sticking with the iPhone 4 for another year, iOS 7.1 makes performance tolerable enough that using the phone isn't unbearable. The benefits to trading up are unmistakable, though—you get better performance, a larger screen, more RAM, faster Wi-Fi and cellular speeds, and a boatload of extra features only available to new hardware. By the time iOS 8 rolls around later this year, you should really think about stepping up.