Apple recently released the iOS 11.2.2 update, which is a dedicated security fix designed to address the Spectre and Meltdown CPU flaws. This has a small impact on performance on PCs, but will it slow down your iPhone, too? We benchmarked several models of iPhones to find out. The short answer? Your iPhone probably won’t slow down as much as you fear.

How We Performed Our Benchmarks

RELATED: How Will the Meltdown and Spectre Flaws Affect My PC?

After the update dropped this week, tech developer Melvin Mughal tested his iPhone 6 before and after updating to iOS 11.2.2 and wrote up the results. After Mughal’s tests, he wrote that:

All numbers point to the same conclusion: it took a serious hit in performance at every possible level. A lot of benchmark levels show a significant decrease in performance on the iPhone 6 up to 50% on some benchmark levels.

Forbes then reported on Mughal’s results, citing a few tweets from users claiming that they also noticed slowdowns.

We ran benchmarks on our own phones, however, and could not replicate Mughal’s results. It’s likely that iPhones are simply not as affected as Mughal originally claimed. Even one of the users cited by Forbes noted that after running the benchmark again, his numbers showed no performance decrease. Another showed much, much smaller performance decreases, more in line with what we’d expect based on what we’ve seen on PCs.

We used Geekbench 4 to run our benchmarks. It performs a number of CPU-related tests to measure both single-core and multi-core performance levels. To run our tests, we made sure no apps were running (even in the background). We ran the same test right before and right after updating to 11.2.2.

We ran these same tests on an iPhone 6s, iPhone 7, iPhone 8, and iPhone 8 Plus, and we looked up some of Geekbench’s public iPhone 6 benchmarks as well. Here’s what we found.

What We Found

In short, we found that none of our phones slowed down nearly as much as Mughal’s iPhone 6. We also did not find evidence of similar slowdowns in the other iPhone 6 results we researched.

iPhone 6

We unfortunately did not have an iPhone 6 to test, but since Geekbench lets users publicly post their scores, we did do a bit of digging. We know an iPhone 6 with a new battery should receive a single core score of round 1600, and we found a number of iPhone 6 scores from iOS 11.2.2 users that are just about in line with what we’d expect (here’s one at 1555, one at 1525, and one at 1475). Those all show around a 10% decrease or less in performance.

There are, of course, other scores that are lower, but it’s hard to determine how many of those decreases are due to the update, and how many are due to low battery health (since Apple throttles phones with old batteries). The only way we can truly know how much this update affects a given phone is with before-and-after benchmarks. But since we know what a pre-update new-battery 6 should look like, we can take the smaller 10% decreases at face value.

iPhone 6s

On the year-old iPhone 6s we tested (which does not have a new battery), we saw a similar performance hit our expectations for the iPhone 6:

  • Single-Core Score: 2000 before update and 1788 after—a 10.4% reduction in performance
  • Multi-Core Score: 3744 before update and 3166 after—a 17.5% reduction in performance
  • Full Results: Results for the iPhone 6s before the update and after the update

Other iPhone 6s scores we looked at did not show as much of a hit, so it’s possible that others may see even better performance than us.

iPhone 7

Our iPhone 7 showed very little reduction in performance, with the multi-core performance rising a bit:

  • Single-Core Score: 3517 before update and 3376 after—a 4% reduction in performance
  • Multi-Core Score: 5907 before update and 6025 after—a 2% increase in performance
  • Full Results: Results for the iPhone 7 before the update and after the update

iPhone 8

Our iPhone 8 showed barely any reduction in performance at all. In fact, the single-core score went up slightly.

  • Single-Core Score: 4240 before update and 4255 after—a  0.35% increase in performance
  • Multi-Core Score: 10,300 before update and 10,254 after—a 0.5% reduction in performance
  • Full Results: Results for the iPhone 8 before the update and after the update

iPhone 8 Plus

Our iPhone 8 Plus also showed a negligible change in performance.

  • Single-Core Score: 4243 before update and 4246 after—a  0.07% increase in performance
  • Multi-Core Score: 10,438 before update and 10,232 after—a 1.7% reduction in performance
  • Full Results: Results for the iPhone 8 Plus before the update and after the update

We have not yet had a chance to test an iPhone 6, but we will update this post when we do.

As you can see from the above results, however, our results show that the performance hit from upgrading to 11.2.2 is not nearly so big as indicated by Mughal’s results with his iPhone 6. Our results do show that that newer phones suffer a milder performance drop than older phones, which we know is happening with desktop PCs as well. But we were not able to replicate anything close to what Mughal saw. And given that other users have seen good results after running the benchmark a second time, we’re guessing there are confounding variables for users claiming a massive slowdown.

All this makes sense, because the 11.2.2 update is really designed to mitigate exploit techniques that affect Safari and other apps that use the WebKit API to display web pages. In Apple’s own support article about these vulnerabilities, they speak to their own benchmark results:

On January 8th Apple released updates for Safari on macOS and iOS to mitigate these exploit techniques. Our current testing indicates that the Safari mitigations have no measurable impact on the Speedometer and ARES-6 tests and an impact of less than 2.5% on the JetStream benchmark.

Of course, these may not be the last updates Apple pushes out for iOS to deal with these vulnerabilities, so we’ll keep this article updated with future developments.

How to Test Your iPhone

Of course, the best way to find out how your phone will perform is to run benchmarks yourself. To run these same tests on your iPhone, you’ll need purchase a 99 cent app named Geekbench. Before you update to 11.2.2, start the app, choose the “CPU” option, and then tap the “Run Benchmark” link.


You’ll get a results screen like this:

Update your iPhone to 11.2.2, and then run the same benchmark again. You can click the “History” tab at the bottom of the Geekbench screen to compare your results, and you can also upload results to the Geekbench site. (Remember, though: if you see a slowdown, try rebooting your phone or waiting a while and running the benchmark again. It’s possible it was slow for reasons other than the Spectre mitigation patch.)

No Matter What, You Should Update to 11.2.2

Our results show that you probably don’t worry so much about slower performance when upgrading to 11.2.2. But no matter what you find, or what other users discover as this story develops, you should definitely install the update. This is an important patch, as it addresses major security flaws, so it’s worth a little bit of a performance reduction, if that reduction exists.

RELATED: You Can Speed Up Your Slow iPhone by Replacing the Battery

Also, if you find that your iPhone shows much lower benchmark scores than you expect (or has just been feeling slow in general), you may be able to speed up your iPhone by replacing the battery. Apple is currently offering battery replacements for a mere $29, so if your iPhone is more than a year or so old, it’s a small price to pay for getting back that sweet sweet speed.

Image Credit: Anna Hoychuk/Shutterstock

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Walter Glenn is a former Editorial Director for How-To Geek and its sister sites. He has more than 30 years of experience in the computer industry and over 20 years as a technical writer and editor. He's written hundreds of articles for How-To Geek and edited thousands. He's authored or co-authored over 30 computer-related books in more than a dozen languages for publishers like Microsoft Press, O'Reilly, and Osborne/McGraw-Hill. He's also written hundreds of white papers, articles, user manuals, and courseware over the years.
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