How to fix my iPhone 6s Plus that is running very slow, keeps lagging, or crashing randomly [Troubleshooting Guide]

Performance issues in mobile devices are usually associated with memory problems like when the device is running low on memory. Common symptoms to show when your device has reached this state would include but not limited to slow or sluggish performance, constant lags when using apps, freezes, and random crashes.

Aside from memory problems, apps glitches and faulty updates can also trigger similar symptoms to occur on any device. There are also other cases when some of these issues are tied to a faulty hardware. This post will address these problems on the iPhone 6s Plus so if you too are trying to deal with any of the aforementioned issues, this might be able to help you. Read on to find out whether or not what you have is tied memory issue or could it be due to physical or liquid damage on your iPhone 6s Plus.

But before anything else, if you have a different issue with your device, visit the troubleshooting page we’ve setup for the iPhone 6s Plus. We list down every problem we address each week in that page so try to see if we’ve already addressed your concern before. If we did, try to use the solutions we suggested and if they won’t work, then you may contact us by filling up this form.

Possible Causes

If you have used your device over time, downloaded and installed tons of complex apps and multimedia contents, then you can say that it is already running low on internal storage and thereby showing performance degradation. Any device can be in this condition as it aged. At first, you will notice a decline in speed and then in the following days or week, your apps begin to respond very slowly, screens get sluggish and websites load up longer than usual, constantly crashing or freezing. While it is possible that these are possible indicators of hardware damage, usually the root cause is in the software layer.

For as long as there are no previous instances of accidental drops or liquid exposure that might have inflicted physical or liquid damage on your iPhone, you still can try some workarounds to speed up your device.

Recommended Workarounds

Given the possibility that the problem is on insufficient memory, you may begin troubleshooting by checking the iPhone’s current memory status. To do so, head over to Settings-> General-> About menu, and then look at the remaining amount of Available storage. You can rule out the possibility of the problem being caused by insufficient memory if you see the Available space is over 1GB (gigabyte). It becomes an issue if the Available memory space is lower than 500MB. In this case, you need to free up some space on your iPhone. Here are your options:

1. Remove unnecessary apps/contents.

Apps, messages, photos, videos, and other contents that are no longer used should be deleted as they take so much space of your iPhone storage. You can start navigating through the Photos app to delete unwanted photos or Messages folder to delete old messages and conversations that are no longer used. You can save time from going through the same process in the future by setting up your Messages app to delete old conversations or attachments automatically when it reached a certain period of time or number limits.

For unwanted apps, just tap on the app’s name and then tap the option to Delete App. To delete audio or music files, swipe your finger from the right to left on the items you want to remove and then tap Delete to confirm action. Aside from deleting, you can also move some of your contents to an external storage media or a computer for backups.

2. Quit all apps running in the background.

Just like what happens when running various programs on the computer, your iPhone can also slow down if you open several apps and let them run in the background. Every time you open an app, that app is loaded into your iPhone’s application memory. The more apps you open, the more your iPhone’s application memory becomes populated until it gets to the point of being unable to accommodate more loads and process requests. This is what happens when you open more apps without quitting previous apps. Even if you’re no longer using the app, it remains running in the background and stays loaded into your iPhone’s memory until you close it. With that said, expect your iPhone to eventually slow down as it already has lots of apps open and running at the same time.

To view all apps that are running and suspended in your iPhone’s memory, open the Multitasking view by double-tapping the Home button. Doing so will open the screen that contains apps previews. Just swipe the app off the top of the screen to close it.

You can also set your iPhone to allow certain apps to continue running even when they’re not open.

  • To do so, go to Settings-> General-> Background App Refresh. On this menu, you will see a list of apps on your iPhone 6s Plus that are currently allowed to keep running even when not open.

If you think you don’t need a certain app to keep running in the background, then you can just turn off Background App Refresh for that app. As much as possible select only a few important apps to stay on.

3. Update your iPhone 6s Plus to the latest iOS version available.

Some would hesitate to update iOS given all the various problems caused by a faulty update or iOS bugs. However, this is not always the case. Should an iOS update messed up your device, just let Apple know so they can work on a solution and roll out a new software update that contains necessary fixes. Thus, if your iPhone slows down after installing iOS 10.3.3, then most likely iOS 11 update will be able to help it to perform better.

4. Reboot your iPhone 6s Plus.

Known as the simplest solutions to various device issues, a reboot gives your iPhone a clean fresh start. Aside from getting rid of minor glitches on the software, a reboot also clears your iPhone’s memory. Cached files including corrupted contents that might have affected your iPhone’s normal functions and operations are likewise eliminated. After the reboot, carefully observe to see if there are any improvement on the overall performance of your iPhone 6s Plus.

5. Reset all settings and restore your iPhone as new.

If none of the previous methods is able to help your iPhone speed up, your next option is a settings reset. It is possible that some of your iPhone settings files get corrupted or a certain app is misconfigured and eventually caused your iPhone to slow down. Tracking down these types of problems can be very difficult, thus resorting to a settings reset can help in rectifying the glitch. Reset All Settings is a process where all your apps and your iPhone’s default settings are restored to defaults. Thus, this should only be considered a last resort. After the reset, you will need to sign in to your apps again.


  • Should you wish to give it a try, backup your iPhone and then head to your iPhone Settings-> General-> Reset-> Reset All Settings. Follow the onscreen instructions to complete the reset and restore your iPhone as new. You will need to re-install and set up everything on your iPhone afterwards.


You can also restore your iPhone 6s Plus using iTunes. To do so, get a computer ready. You can use either a Windows PC or Mac computer to carry out the process. Also make sure that your computer has the latest version of iTunes installed. Once you’re all set, follow these steps to restore your iPhone in iTunes:

  1. Open iTunes on the computer.
  2. Connect your iPhone 6s Plus to the computer using the supplied USB cable.
  3. Wait for iTunes to recognize your device or tap the option to Trust This Computer to proceed.
  4. Select your iPhone 6s Plus from the list of available devices in iTunes.
  5. When prompted, select the option to Restore your device and set it up as new.

Follow the onscreen instructions to complete the restore process then set up your iPhone.

Seek More Help

If the problem persists or your iPhone 6s Plus is still running very slow, keeps lagging, or crashing after the reset or iTunes restore, then your next option would be to escalate the problem to Apple Support for other recommendations. In case you suspect that a physical or liquid damage is present and might have caused you these troubles, you can take your iPhone to an authorized service center instead, for hardware assessment and/or repair.

Connect with us

We are always willing to help fix your problems with your Apple device. Browse through our existing troubleshooting posts or you may contact us directly by completing this form and hitting the Submit button. Make sure you provide all the necessary information about your phone and the problem so that it would be easier for us to help you.

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