iPhone 6 very slow with IOS 11 update

HERE'S THE FIX: Go into Settings> General> Reset> Reset All Settings (this will reset iOS settings, won't touch your apps)

WHAT THIS DOES: This will *not* erase your phone, but will reset most of the things you can adjust in settings on iOS (you'll need to re-enter you wifi, adjust notifications and privacy settings again, reset your default account for Calendar and Notes, etc, but all your email accounts and iCloud account will still be logged in and all working).

FIXES THIS ISSUE: I had the same issue: iPhone 6S. Upgraded. Even with 25GB free, I'd press a button and often have to wait 1-3 seconds for a response, or copy and paste selectors would be really slow to appear, even the keyboard was unresponsive... phone was barely unusable, literally. I think most people don't get it because most who updated to iOS 11 noticed it being a little slower but not 90% slower. Those like us need to take this step.

BACKGROUND: When I was scouring I found that erasing your phone and restoring from backup worked for people on Reddit, and that should be reliable. I was in the process of doing that myself and accidentally chose "reset all settings" instead of "erase all content and settings". My phone rebooted and all my apps are fine, just needed to go through iOS settings and readjust things.

ALTERNATIVES: This is obviously better than either (a) downgrading to iOS 10 or (b) making sure your phone (as it is now on iOS11) is backed up to iCloud, erasing it, and restoring from that backup.

The difference in speed is shocking.

Pretty sure this will work for you too.

Apple just confirmed that they are throttling phones that have degraded batteries, to prevent the phones from spontaneously shutting down.

Our goal is to deliver the best experience for customers, which includes overall performance and prolonging the life of their devices. Lithium-ion batteries become less capable of supplying peak current demands when in cold conditions, have a low battery charge or as they age over time, which can result in the device unexpectedly shutting down to protect its electronic components. Last year we released a feature for iPhone 6, iPhone 6s and iPhone SE to smooth out the instantaneous peaks only when needed to prevent the device from unexpectedly shutting down during these conditions. We’ve now extended that feature to iPhone 7 with iOS 11.2, and plan to add support for other products in the future.

There's an article about it at Tech Crunch: https://techcrunch.com/2017/12/20/apple-addresses-why-people-are-saying-their-ip hones-with-older-batteries-are-running-s…and another one at the Verge: Apple confirms iPhones with older batteries will take hits in performance - The Verge

Glad to have an unequivocal statement from Apple. It sounds like they won't be issuing a fix. (This *is* the fix.) Time to replace my batter.

Replacing the battery is the only way for your phone to regain full performance - and that at all battery load levels.

I just had this done this morning. Now my phone runs at the nominal CPU frequency (1400MhZ) just like when it was new.

There is no "big mess" to solve. All Apple did was to gradually reduce CPU speed as the battery degraded to protect it and extend its life (and prevent sudden phone shutdowns).

So, helped a friend today; same issue...great deal of lagging in particular - we reset all network settings. We recovered data from iCloud backup during set up.

Tested it - still a bit slow for her taste, and I had to concur

- So, then went into Settings-General-iPhone Storage and began cleaning up apps.

This was a HUGE help. ***We got rid of a lot of data in "Review large attachments" (5 GB)*** - she had no idea attachments were in there

Essentially, freeing up this space on the device itself gave it room to "breathe" and function much better. Her system was overwhelmed.

- Backed all photos and content to iCloud again and removed what we could off of the device.

Removing apps or app data from your iPhone storage is a smart idea anyhow and it was a great help to her.
Her 6 is running smooth again.

Hope this status update helps!

About storage on your device and in iCloud - Apple Support

Hello everyone, (Fixes for slow performance)

After spending a bit of time reviewing everyone's issues with iOS 11 on an iPhone 6, I have left some suggestions below. If your iPhone is slow, laggy, or hanging, follow these simple steps below:

Reset iOS Settings

This erases no data, or apps, but Touch ID, wallpaper and some settings will have to be reconfigured after the reset. To perform this action, go to Settings > General > Reset > Reset All Settings.

Update to the latest version of iOS 11 (currently iOS 11.1.2)

The latest version of iOS 11 includes bug fixes, security updates and performance updates. The latest version of iOS 11 is iOS 11.1.2. To update to iOS 11.1.2 go to Settings > General > Software Update, and download and install the latest update of iOS 11. I will update the title to always show the latest version of iOS. iOS 11.2 will be coming soon so that might fix some issues for you

Delete apps and games you don't use

If your iPhone is running out of storage, delete apps, games and media you no longer use. A good recommendation is to keep a few GB extra, for example if you have a 16GB iPhone, keep at least 3GB free. This may seem like small thing, but doing this will keep your iPhone running effieienctly

Disable advanced visual effects

In Settings > General > Accessibility > Reduce Motion and Settings > General > Accessibiloty > Increase Contrast > Reduce Transparency disable these for a faster iPhone

Last Resort: Restore your iPhone to factory settings using iTunes and don't restore the backup

Manually backup everything, drag and drop photos, music and videos first, don't create a backup, then

Restore your device in iTunes using a Mac or PC running iTunes 12.7.1. This will reinstall iOS, not just "reset" it. After this has done manually reinstall Apps & Games from the App Store, then drag and drop photos back into iTunes and sync. Restoring a backup restores the problem as well. Especially for an older device like the iPhone 6 do this.

I am more than happy to help you, because for me I am using iOS 11 on the latest devices, and performance and battery life have never been an issue for me, at all.

Thanks,

Vis

<Edited by Host>

I replaced the battery today, and I have to report that my iPhone 6 plus is snappy and quite responsive. Testing determined that the battery was "bad" with ~35% wear. The techs at Sprint were skeptical that replacing the battery would help, but so far, it's been a worthwhile spend. Will post more in a day or two. Early today, before replacing the battery, the phone was degraded to the point that folks on the other end of my calls couldn't hear me. That was the last straw! Chin up, and fingers crossed.

No computing devices can work properly if they are close to being filled with data!

iOS needs an absolute minimum of 2-3 GBs of free data storage space to function nominally or with near average performance.

If an iDevice can maintain closer 4 GBs, or so, iOS performance should return to more normal, expected levels.

Many users run their computers and mobile devices down to the point where the operating systems have NO amount of data space to function properly!

Also, mobile devices have limited RAM.

Users who leave scads and scads of apps in the Background app switcher that are still running active in the background and constantly grabbing up to date data from the Internet, eats of RAM, CPU cycles and other resources, like your battery.

AND to add insult to injury if you leave a web browser open with scads and scads of active website tabs, ths eats into RAM and CPU cycles and another hit on battery life!

So, it’s important to not max out available hardware, software and data storage resources of any computing device!

I have some more data, and a possible workaround until Apple fixes this problem.

Using the utility CPU DasherX, I can watch the clock rate of the CPU in my iPhone 6 change when the battery charge level changes.

When the battery is at 93%, the CPU runs at 1127 MHz, which is pretty close to 1.4 GHz it's rated for.

When the battery drops down to 90% the CPU drops to 839 MHz.

When the battery drops down to 89% the CPU drops to 600 MHz.

When I charge the phone, the CPU speed tracks upward at the same points. Back up to 90% battery, the CPU goes back to 839 MHz. Back up to 93% battery, the CPU goes back to 1127 MHz.

I could pay $80 and replace the battery on my phone. People have reported that fixes the problem. But I don't really want to spend $80, and it's not clear how long the fix will last. Maybe when the new battery starts to age, the problem will come back. I'm also still hopeful that Apple will acknowledge and fix the underlying bug.

My workaround in the meantime is to use an external battery back all the time. If I can keep the built-in battery fully charged, then the phone will keep running at full speed. And when Apple fixes the problem, I'll still have a useful external battery pack. Sure, I'm stuck carrying it around, but they make some pretty slim ones these days, so it might not be that bad.

Fixed!

I finally found the culprit (I think)!

I changed the battery for a new one as suggested here and now the phone runs smooth again.

I imagine apple charges around 90 ~ 100€/$, but I bought it in ifixit for around 30€ with all the tools needed to do it myself.

It's not a procedure for the faint hearted tho, I must have given the screen an electrostatic shock or something and 4 vertical lines appeared in it. I was so worried... but they seem to be dissapearing as time goes by. Phew.

It's worth it tho, i was about to sell it.

mjestic wrote:

It's been two weeks since I replaced the battery in my 6 plus, 64GB iPhone and wanted to provide an update.

Thank you, that's very thoughtful, and the information you provided is very helpful.

Performance has remained significantly better since the replacement; however, there are definite correlations between performance and battery state. When the charge is below 50%, there are very noticeable performance hits,

If you want, you can measure this effect by getting a an app that measures CPU performance. One example is CPU DasherX. I found that when my battery level drops to certain specific levels, the CPU clock rate drops. For example, it initially runs at more than 1100 MHz, but then drops down to just over 800 MHz when the batter charge goes below 90%. It was nice to know I wasn't imagining things, and also to demonstrate clearly that the performance problems are related to battery level.

One way to address the problem is to buy a battery case. You can get these for as little as $15. They are a little bigger than a regular iPhone case, but for me it is worth the tradeoff. If my iPhone battery starts to go down I just push a button on the back of the case and the phone charges back up to 100%. So I pretty much never have to deal with the performance issues.

especially with scrolling down pages and lists; iMessager is slow to respond, the native email app is degraded, and screen orientation definitely takes a hit. I rely on this phone for business and there are times when I want to toss it out the window when I'm stuck waiting for a process to complete before the app returns. As I posted in previous threads above, I have restored this device to a native state and re-installed just the essential apps from the iTunes store. I have over 40GB free storage, and I've disabled most, if not all the "fancy" features. So, in conclusion: a fresh battery will definitely improve the overall performance and make the phone generally usable, don't expect that to restore it to it's previous Apple glory.

Thank you again for sharing your experience. It's very helpful information.

This worked for my iPhone 6. Resetting to factory settings worked. The other methods did not work for me. The difference is that only resetting to factory settings wipes the phone and does a clean install of the iOS. This indicates that the over the air update (applies ”patches” I think) broke the iOS for some phones.

Here’s what I did:

Backup iPhone 6 to computer using iTunes and encryption.

Restore the phone to factory settings. iTunes will download the newest iOS and may take a while.

Set up as new phone.

Restore from backup.

Do some housekeeping.

Done.

CPU Dasher confirms that CPU running at 1127 MHz after factory reset vs. 600 MHz before reset.

I think that there was more happening than just slower CPU. Non-responsive home button cannot be due to slower CPU.

I hope that this works for you.

I believe what you're seeing is an old battery behaving inconsistently. The throttling happens in response to decreased voltage from the battery. Temperature and other factors can affect that, as well as charge level. It could also be affected by which cells within the battery are holding the charge. Short story: getting a new battery ($80 from Apple) should fix the problem, at least for as long as that battery lasts.

"They won't stand behind their screwing us."

What makes you say this ? We all know what happened and Apple admitted our collective analysis, namely: a change introduced in iOS11 gradually reduces the frequency of the CPU of the phone if the battery is detected as approaching end of life (2 years+, 500 cycles+). It does so to prevent the abrupt shutdowns of the phone that would happen even when the battery seemed to be sufficiently loaded. The effect is really to extend the useful life of your battery. This has all to do with the chemistry of batteries: they decay over time. The batteries in your radio decay. The battery in your watch decay. The battery in your car decays. It's a fact of life. Maybe future developments in battery technology will improve their lifetime ... What this is really all about is a PR failure for Apple.

"The only fix will be to buy a new iPhone."

That is blatantly false. You just need to replace the battery. And after all the hoopla, Apple agreed to replace them at a fraction of the cost. Also a planned iOS update should make the throttling optional, or maybe less aggressive (speculating here).

MichelPM, yes I did.

Just before Apple admitted the CPU throttling and following the findings presented in this same thread, I ordered a new battery from ifixit and changed it myself (there is an old post around here where I explain this). Also I checked with CPU Dasher that my CPU went back to 1400MHz.

To sum up: The phone is performing much, MUCH, better, it is now usable, but usable is not what I expected from a 1000€ phone.

Besides a general clunkiness that is clearly noticeable in every aspect, and that was not there with iOS 10, which was butter smooth, I'm still experiencing the following issues:

-The keyboard is still suffering from mini freezes randomly, albeit it performs far better than it did before the battery replacement.
-Siri sometimes takes 10 to 15 seconds to start listening when long pressing the main button, even more when saying 'Hey Siri'. And many times she starts thinking for a while (after receiving whichever order I gave) and eventually just does nothing and closes.

-Fast forwarding (or rewinding) music or podcasts sometimes (many times) does the opposite thing.

-Many emails just don't load when trying to read them, I have to close the mail app and open it again.
-Sometimes the camera app takes ~10 seconds to open, others just 2 or 3. Taking pictures is also laggy.

-Youtube suffers from ~10 second freezes when receiving user input or when ending a video, and sometimes does not orient the screen properly (this could be youtube's problem, but it worked fine on iOS 10).

Maybe you are right and it all gets better when they let us opt out, maybe all those micro stutters is the throttling jumping in for a micro second, maybe ifixit batteries are just not as good as apple's, we will see.

In any case, I STRONGLY recommend to have your batteries replaced, the performance improvement is huge.

How do you use your iPhone?

Use is a factor, too!

Some users work their iPhone harder than others and that can have an effect on speed/performance of any iPhone due to limited RAM and CPU resources.

Have you tried a hard reset of your iPad by holding down both the Home and sleep/wake buttons simultaneously until your iPad goes to black and restarts with Apple logo, then release the buttons?

How much free data storage space is actually left on your iPhone.

iDevices need to maintain a minimum of 3 GBs, OR greater, free data storage space.

In Settings app, General settings panel, turn OFF Background App Refresh.

Settings app, under General settings, Reset panel, at the right bottom of the list, Reset All Settings.

In Settings app (NOT from the iOS Control Panel) turn OFF Bluetooth when not using any Bluetooth devices.

Also, in general, if you want a faster IDevice, on all of my iDevices, I turn off most of the iOS motion graphics eye candy, by simply turning ON Reduce Motion in Settings app, General, Accessibilty settings.

Make sure you aren't running scads and scads of background apps in the iOS 11 Control Panel/App Switcher.

If you are, you need to quit the bulk of these background running apps by tap and hold a finger on an app window in the switcher and slide your finger upwards to quit an app. You should be able to use more than one finger to quit more than one app window simultaneously.

Also, make sure you don’t have scads and scads of active website tabs running in the web browser.

If you do, greatly reduce the amount of active website tabs your web browser.

Good Luck to You!