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How To Fix iPhone 15 Running Slow and Speed Up The Performance | 15 Proven Tips

Written by: Karl Leuang



Time to read 10 min

iPhone 15 running slow can be fixed quickly

Is your iPhone 15 laggy and running slow lately? Do apps keep loading? Is the screen frozen when switching to the camera for a quick snap?

A slow iPhone 15 can be such a frustration. Today, we would like to talk about the common causes of a laggy iPhone 15 running slow and show you tips on how to fix the iPhone 15 running slow and speed up the performance. 

Root causes of iPhone 15 running slow

an iPhone 15 in a fire back groun with words: top causes of iphone 15 running slow

There could be various reasons for your iPhone 15 running slow. Still, the four most common ones are:

1. Not update to the latest IOS version

Apple improves its iOS every day by collecting feedback from millions of customers and adding more new features to optimize both the hardware and software.

If your iPhone 15 is running slow, the outdated iOS is always the first root cause.

2. Not enough storage space

Your iPhone 15 is running slow if your storage is getting full.

When we run the iPhone 15, the system will generate many temporary files to keep the operation smooth.Without enough space, it will be difficult to keep the phone to collect data and run the operations.

3. Too many demanding APPS running in the background

When the apps run in the background, most still take the A17 CPU to process the tasks. They will slow down the CPU and make your iPhone 15 run slow

4. Glitching system settings and software installation

If you set up the system glitchy or install some corrupted apps without fixing them, the iPhone 15 running slow will result. 

5. The hardware issues

Hardware issues on iPhone 15 causing slowness are uncommon, but overheating and insufficient storage can be culprits. Try checking your phone's temperature and storage to rule them out.

Now, it is time for us to fix your iPhone 15 running slow the 15 tips below

15 Tips To Fix iPhone 15 Running Slow

a iphone 15 in the picture with 15 tips how to speed up iPhone 15

1. Keep your iPhone 15 with latest iOS update

Updating your slow or laggy iPhone 15 to the latest iOS will solve most problems.

To update to the latest version of iOS:

  1. Back up your device: This is a crucial step to ensure you don't lose any data during the update process if you have an issue. You can back up to iCloud or your computer.
  2. Connect to Wi-Fi and power: Make sure your iPhone 15 is connected to a stable Wi-Fi network and plugged into power.
  3. Go to Settings > General > Software Update.
  4. Download and Install: Tap "Install Now" to download and install the update. Your iPhone may restart several times during the process.

You can enable automatic updates on your iPhone 15 to ensure that it always has the latest version of iOS.

  1. Go to Settings > General > Software Update.
  2. Tap on "Automatic Updates."
  3. Turn on "Download iOS Updates" and "Install iOS Updates."

2. Update all your app

The App Store has stringent rules and regulations to ensure that all apps perform as they should without stealing our performance and creating problems.

Update apps on your iPhone 15 will give you better security, faster performance, and cool new features!

There are two ways to update apps on your iPhone 15:

  1. App Store: Open the App Store, tap your profile picture, scroll down to see updates, and tap "Update" next to the app you want to update, or tap "Update All" for all apps.

  2. Automatic Updates: Go to Settings > App Store and turn on "App Updates" for automatic updates over Wi-Fi.

3. Optimize iPhone 15 storage

Like us, the iPhone 15 needs space to think, work, and dance! If you do not offer enough storage, the iPhone 15 running slow is inevitible.

Here are some quick ways to optimize storage on your iPhone 15:

  1. Review Photos & Videos: These often take up the most space. Use iCloud Photos with "Optimize iPhone Storage" to store full-resolution versions in the cloud and keep space-saving versions on your phone https://support.apple.com/en-us/108922 .
  2. Offload Unused Apps: Don't delete them entirely! Offload lets you keep app data while removing the app itself. Reinstall later to regain functionality. Go to Settings > General > iPhone Storage, tap an app, and choose "Offload App."
  3. Clear Temporary Files: Go to Settings > General > iPhone Storage. Look for large system files like Safari downloads or message attachments and delete them if needed.

4. Turn off background app refresh

Background App Refresh is one of the most common reason why your iPhone 15 running slow. It allows your apps to download new content in the background even when you're not using them. 

To turn off Background App Refresh, follow these steps:

  1. Open Settings on your iPhone.
  2. Scroll down and tap General.
  3. Tap Background App Refresh.
  4. Toggle off the switch for the apps you don't want to refresh in the background.

Attention: Messaging apps are an exception. You should keep them on so you can receive notifications for new messages.

5. Turn off push mail

Push mail keeps your iPhone constantly connected to the email server to check for new emails. Push Mial can drain battery life and slow down your iPhone's processor.

To turn off push mail, follow these steps:

  1. Open the Settings app on your iPhone.
  2. Scroll down and tap Mail.
  3. Tap Accounts.
  4. Tap Fetch New Data.
  5. Turn off the switch next to Push.

You can choose how often you want your iPhone to check for new emails, such as every 15 minutes, every 30 minutes, or hourly.

6. Clearing history and website data in Safari

Clearing history and website data in Safari can speed up your iPhone. Here are the steps on how to do it:

  1. Open the Settings app on your iPhone.
  2. Scroll down and tap Safari.
  3. Scroll down to Clear History and Website Data.
  4. Tap Clear History and Website Data.

You can also scroll down to Advanced, then tap on Website Data and Remove All Website Data at the bottom of the menu to remove all website data while preserving your history.

7. Close apps on iPhone 15

Running apps in the background will consume CPU and power, and closing unused apps will improve the iPhone 15's speed.

Here are the steps on how to close apps on iPhone 15:

  • If your iPhone has Face ID, swipe up from the bottom of the screen to the center of the screen to open the app switcher.
  • If your iPhone has a home button, just double press that home button then swipe your apps up and off the top of the screen.

8. Offload unused Apps ( If you can not find out the problems)

If you're experiencing a sluggish iPhone and can't pinpoint the cause, consider offloading unused apps as your first step. This process removes the app from your device, freeing up valuable storage space, while retaining all your data and documents. This means you can reinstall the app at any time, with all your data intact, whenever you need it.

There are two ways to offload apps on iPhone 15 (assuming it uses iOS 17):

Method 1: Offloading a Single Unused App

  1. Open the Settings app on your iPhone 15.
  2. Scroll down and tap General .
  3. Tap iPhone Storage .
  4. You'll see a list of apps using storage. Tap on the specific app you want to offload.
  5. Look for the Offload App option. Tap it.
  6. Confirm that you want to offload the app by tapping Offload App again.

Offload App removes the app itself from your phone, freeing up storage space. However, your documents and data for the app are preserved. You can reinstall the app from the App Store later and regain your data.

Method 2: Automatic Offloading of Unused Apps

  1. Open the Settings app on your iPhone 15.
  2. Scroll down and tap App Store .
  3. Swipe down to the bottom of the page.
  4. Look for the toggle switch next to Offload Unused Apps .
  5. Tap the switch to turn it ON .

This enables automatic offloading. When your iPhone storage gets low or after a certain period of inactivity for an app (iOS typically sets this at 12 days of non-use), the system automatically offloads unused apps for you.

Remember, offloading an app doesn't delete your data. You can always reinstall the app and pick up where you left off.

9. Removing unneccsary Widgets

Widgets are one of the newest 15 features of the iPhone that people love. However, they consume a lot of battery and power. Removing unnecessary or unused widgets will prevent your iPhone 15 from running slowly.

There are two ways to remove unnecessary widgets from iPhone 15:

  • The first way is to go to the home screen where the widget is located. Press and hold on to the widget until a menu pops up. Then tap "Remove
  • The other way is to go to Settings > General > Home Screen & Dock. Then turn off the switch next to the widget you want to remove.

10. Turn off low power mode

turning off Low Power Mode can actually speed up your iPhone. Low power mode limits the amount of power the processor can use, which slows down your iPhone. Disabling low power mode allows your iPhone's processor to use more power and run at higher speeds. 

11. Turn off Siri

By turning off Siri on your iPhone 15, you can significantly enhance your device's battery life, avoid unintended activations, and optimize performance by reducing background activity.

There are two ways to disable Siri:

  1. Turn off voice activation:This prevents Siri from activating when you say "Hey Siri" or use the side button.
    • Open Settings .
    • Scroll down and tap Siri & Search .
    • Under "Listen For," choose Off . (This option might be under a separate menu depending on the iOS version).
  2. Turn off Siri completely:This disables Siri for all functions, including voice activation and button presses.
    • Open Settings .
    • Scroll down and tap Siri & Search .
    • Toggle off both "Listen For..." (or similar) and "Press Side Button for Siri."

Important Note: There have been reports of issues completely turning off Siri in iOS 16.4.1. The "Listen For..." toggle might not entirely turn off voice activation if you're on this version. Try the steps above and see if it works for you. Otherwise, you might have to wait for an iOS update to fix this bug.

12. Turn off location service on non-essential apps

Location services are helpful for many apps but can also drain the battery and potentially slow down performance. Disabling them for non-essential apps can help. Here's how to turn off location services on iPhone 15:

  1. Open the Settings  app on your iPhone 15.
  2. Tap on Privacy & Security .
  3. Find and tap Location Services .
  4. You'll see a toggle switch for Location Services at the top. Tap the switch to turn it off.

13. Force restart your iPhone 15

A force restart on iPhone 15 can fix minor software issues and improve performance by clearing temporary files.

Forcing a restart on your iPhone 15 is a quick process:

  1. Quickly press and release the Volume Up button.
  2. Quickly press and release the Volume Down button.
  3. Then, hold the Side button (on the right side) until the Apple logo appears on the screen. Let go of the button when you see the logo.

It's helpful but optional for everyday use. Please only do it if your phone keeps frozen all the time.

14. Keep your iPhone 15 cool

A hot iPhone 15 is likely to experience lag and slow performance.

Here are some tips to keep your iPhone 15 cool:

  1. Avoid direct sunlight or hot environments when charging your phone.
  2. Use an authentic Apple charger and cable.
  3. Consider using a slim case. Many people don't realize that a thick phone case can trap heat, slowing down their iPhone 15.

We would recommend Thinborne - the thin phone case maker from Texas for your iPhone 15 case choice. 

15. Factory Reset your iPhone 15

Factory reset wipes all data but can fix major software issues, improve performance (sometimes), and prepares your iPhone for sale/trade-in.

(Remember, this will erase all your data!)

Here's how to factory reset your iPhone 15:

Ensure you back up your phone before proceeding (through iCloud or your computer).

  1. Open the Settings app on your iPhone 15.
  2. Scroll down and tap General .
  3. Tap Transfer or Reset iPhone .
  4. Tap Erase All Content and Settings .
  5. You might be asked to enter your Apple ID password or device passcode.
  6. Confirm that you want to erase everything by tapping Erase All Content and Settings again.

Your iPhone will then begin the reset process, which may take some time. Once finished, your iPhone will restart and be set to its factory defaults.


If none of the tips above fix your iPhone 15 running slow, you might need to contact Apple service to check if there are any hardware issues like broken components, batteries, and more. 

Final Thoughts

In conclusion, iPhone 15 running slow is common.

However, there are ways to fix iPhone 15 running slow and speed up the performance.

By following the 15 tips mentioned above, you can ensure to fix iPhone 15 running slow by yourself. 

About Author

Karl Liang

A son, a husband, and a father.

I am A tech geek from Frisco, Texas, running Thinborne, a company offering super-thin phone case made of 600d aramid fiber. 

I share my passion and knowledge for all things tech with anyone who wants to listen!

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