Here's why your older iPhone may get slower over time

One of the major annoyances in the tech world is when your device, be it a smartphone or a computer, gets slower and slower as time passes by. Leaving aside the notion of planned obsolescence, there are various reasons as to why the performance of a device may worsen over time. For example, if your laptop gets clogged with dust, this could prevent the heat from properly dissipating into the heat sink, causing the machine to run hot and consequently to reduce its CPU speed to prevent it from overheating. This can indeed lead to slowdowns, but then there's the software side of things – having too many apps boot at startup and running in the background can also lead to decreased performance.

But what about smartphones? Well, smartphones also tend to get slower over time, and getting to the root cause is very complicated, especially seeing as how Android and iOS are two very, very different beasts. And although we can't offer a universal answer at this point, we at least have some interesting anecdotal information as to why some older iPhone models, at least the 6 and 6s, are getting slower as time goes by.

If you recall, Apple last year launched a repair program for iPhone 6 and 6s users affected by seemingly random shutdowns, offering free battery replacements. However, since further investigation revealed that the number of affected devices was larger than initially anticipated, Apple set out to fix the issue with a software update, in iOS 10.2.1. When the update was rolled out, it was not exactly clear how Apple had managed to reduce random shutdowns by around 80 percent, but the general consensus was that some adjustments to the power management system in iOS had to be made in order to achieve this.

A Reddit thread popped up this weekend—spotted by 9to5Mac—that offers some interesting insight on the matter, and possibly an answer as to why many iPhone 6 and 6s users are experiencing slowdowns. Basically, it turns out, the software fix that Apple created was aimed at dynamically changing the maximum clock speed of the CPU depending on what voltage the battery is outputting at the moment, so as to prevent the phone from drawing too much power and shutting down. This, of course, means that those who didn't get in on the battery replacement program, would get slower and slower performance from their phones as the batteries deteriorated. Users who had their batteries replaced, on the other hand, report greatly improved performance.

Here's what a Reddit user reports after running GeekBench on his iPhone 6 Plus:

And there you have it. Apple has been implementing similar techniques for adaptive power management in MacBooks, but we now have good evidence that this may very well be the case with the iPhone 6 and 6s as well. But even if you opt to have your battery replaced, which will indeed boost the performance of your phone, keep in mind that as the battery ages, it will worsen again (if you haven't upgraded to a new device by then).

As for what the future holds for the latest crop of iPhones, 9to5Mac notes that Apple’s A10 and A11 chips are engineered to manage tasks in a different way, by allocating them between cores depending on how demanding they are, which is supposed to help separate actual performance from battery health.

source: Reddit via 9to5Mac



1. zenun12

Posts: 205; Member since: Oct 31, 2016

839/1377? My Galaxy S4 just outperformed a 6 Plus...

2. worldpeace

Posts: 3135; Member since: Apr 15, 2016

Congrats.. #walkaway

4. NickHill

Posts: 388; Member since: May 07, 2016

Well, 6 Plus isn't laggy even after the slow down.

13. EcoCare

Posts: 444; Member since: Jul 30, 2014

That's a very subjective statement right there. My friend just got a new 6 Plus with iOS 11 and the animations were choppier and apps load slower than my Chinese Android phone which is released in 2014 as well.

23. firebird820

Posts: 157; Member since: Jan 01, 2017

Maybe it's because your Android phone is Chinese and from 2014. There's a reason those phones are only like $100 now, it's because they're pieces of crap. Why don't you save up your money and actually work hard to get a new Android phone and not some Chinese company that probably has no experience with making phones anyway. It's not Android's fault you can't afford a nice phone.

25. TheOracle1

Posts: 2340; Member since: May 04, 2015

What does your reply have to do with what he said? How do you know he doesn't have the latest Android phone? I have a 2014 Asus Padfone X, a 2016 Xiaomi Redmi Note 3 and a 2017 Huawei P10. I commented below how my 2014 Asus is still working perfectly too. Does that mean I can't afford a good phone too?

26. KingSam

Posts: 1505; Member since: Mar 13, 2016

You dont know a person's financial situation so dont make those statements. In a thord world country that extra $100 or $200 is a big difference because of weak currencies.

27. blkkobra

Posts: 44; Member since: Jan 22, 2014

Your comment only succeeds to make his argument even more embarrassing to Apple fans. If a "piece of crap" $100 Chinese Android is outperforming a $500+ iPhone 6 plus, how does your comment redeem Apple in any way?

36. firebird820

Posts: 157; Member since: Jan 01, 2017

It doesn't. That's my point. I don't like Apple. I thought that would be pretty obvious

3. piyath

Posts: 2445; Member since: Mar 23, 2012

The problem is in the battery not in the CPU or software. Just replace your battery and you'll be fine. A new battery will last at least 2 years before showing any slow downs again.

7. RebelwithoutaClue unregistered

But by throttling the CPU without any notice, people won't know the battery need replacement. And a slower phone might be several reasons, so the link to the battery isn't easily made. And it still throttles when the phone is on the charger, which is a weird thing to do.

14. BGChicago

Posts: 227; Member since: Nov 16, 2014

I would be cautious about the 2 years advise. LiOn starts to degrade even after 3-400 charge cycles. At 500, it's sensible. How many people charge their phone every day? 2 years would be over 700 cycles for most.

28. ColinW

Posts: 413; Member since: Jun 04, 2014

Tell that to all the iPhone 7 users that experienced a sharp fall in battery life after installing IOS 11!

29. bucky

Posts: 3795; Member since: Sep 30, 2009

What users? I had an iPhone 7 and noticed no difference after the 11.1 update.

6. TerryD

Posts: 560; Member since: May 09, 2017

So what you're saying is that Apple are now throttling devices depending on the condition of your battery. So older device means your battery is more than likely on the way out, so your clock speed is reduced. Tell me again how Apple aren't building obsolescence into the old phones?

10. Milen_Y

Posts: 116; Member since: Jun 09, 2016

Apple is doing this to keep your iPhone from drawing too much power (and shutting down as a result) when the battery can't handle it. All batteries deteriorate over time, nothing we can do about this.


Posts: 2817; Member since: Oct 03, 2012

So this means that apple is using crappy batteries! Even my old Nokia phones from 10 years a go are working fine!

12. kiko007

Posts: 7520; Member since: Feb 17, 2016

Have you ever taken the time to consider that their working condition is directly related to your. non-usage of the devices? Hard for batteries to drain when you don't use the phone regularly.

15. TheOracle1

Posts: 2340; Member since: May 04, 2015

I still use my 2014 Asus Padfone X every day which is still on Kitkat (stupid At&t) and have no such issues. Battery is ok and the Snapdragon 801 is ticking along nicely. It's my back up tablet and used primarily for gaming and watching TV. So your premise is flawed.

16. Back_from_beyond

Posts: 1472; Member since: Sep 04, 2015

I owned a Motorola Razr Maxx that worked for 4 years and was charged just about every single day i owned it, yet it never diminished in performance or charge capacity. there are Li-ion batteries that can easily go 1000 recharge cycles before they start losing capacity and charge. So maybe SIGPRO isn't wrong about to state that. Apple themselves have claimed that iPhones only have a 1 year warranty, because that's the expected life cycle in a courtcase not long ago that covered warranty.

17. NarutoKage14

Posts: 1346; Member since: Aug 31, 2016

This will just make people think it's about time they buy a new iPhone due to Apple not revealing the intentional cause. Pretty much the definition of planned obsolescence.

21. TerryD

Posts: 560; Member since: May 09, 2017

So how do you know if you're being throttled? Is there a check you can run to find out if you're suffering from this issue? Will every phone get throttled to a proportional extent or is it just when the battery degrades past a certain threshold?

18. Valdomero

Posts: 704; Member since: Nov 13, 2012

I have a recent iPhone 6 with iOS 11.1.2 and it's been quite smooth experience. It sometimes freezes or randomly shutsdown like 1 every 1-2 months, but overall it's having a good behavior. Also for obsolescence you need to consider the app's system requirements, every day apps are updated to the current OS, thus including more code into the software, translating into more processing from the CPU.

19. xfire99

Posts: 1207; Member since: Mar 14, 2012

Soon the Vampires will awake and start a mass action law suits vs Apple.

20. Peacetoall unregistered

Too bad it won't happen

22. firebird820

Posts: 157; Member since: Jan 01, 2017

"Adjusted clock speed..." Or, the real reason, Apple bricks their phones purposely so people will buy their new ones and give them more money.

24. HansP

Posts: 542; Member since: Oct 16, 2011

Apple's blanket solution to all issues: install a slow firmware on older devices which will make you want to buy a new model. Congratulations sheep for being sheep.

30. LouisMariano5

Posts: 63; Member since: Sep 22, 2014

another words apple intentionally wants to f*ck your phone up so you'll buy a new one.... DUH !

* Some comments have been hidden, because they don't meet the discussions rules.

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