iPhone Slow and Laggy After iOS 18 Update? Here’s How to Fix It

Is your iPhone slow after the iOS 18 update? This issue is common with recent iOS versions, and many iPhones feel sluggish and unresponsive.

Fortunately, It’s usually an easy fix. We’ve rounded up tried-and-true methods that actually work to get your iPhone running like new. Let’s jump in!

Why Is iPhone Slow After iOS 18 Update?

Many users report performance issues with their iPhones after updating to iOS 18. In fact, this thread on the Apple Support Communities highlights the same problems: lag, app freezes, and slower system animations.

Why does your iPhone suddenly slow down? After an update like iOS 18, your phone kicks off several background tasks. These necessary processes, which re-index files, update app databases, and recalibrate system components, slow down your phone temporarily. On top of that, some apps might not be fully optimized for iOS 18 yet, which can cause crashes or delays. Features like dynamic wallpapers and Background App Refresh can also put extra strain on your phone.

If you’re using an iPhone model older than ~3 years, the update might hit harder—many users on different forums report their devices feel slower, especially with apps that worked fine before the update.

How to Fix iPhone Lagging After iOS 18

If your iPhone feels sluggish after updating to iOS 18—there are a few fixes that can bring it back up to speed. These tips tackle common issues like background app activity, heavy animations, and resource-draining settings. Let’s start with something easy: closing unnecessary background apps.

Method 1: Close Unnecessary Background Apps

One of the simplest ways to speed up your iPhone is to close any apps running in the background. Although iOS manages memory well, having too many apps open at once can cause slowdowns, especially on older devices.

1. Swipe up from the bottom of the screen (on iPhones with Face ID) or double-press the Home button (for the iPhone SE 2nd and 3rd generation, as they are the only models with a Home button that support iOS 18) to access the app switcher.
2. Swipe through the list of open apps.
3. Swipe each app upwards to close it.

Close unnecessary apps to free up system resources, which makes your iPhone run faster. However, this is just the first step. Other factors, such as outdated apps or system settings, can also contribute to iPhone lagging after iOS 18.

Method 2: Clear iPhone Storage

Another thing that significantly impacts your iPhone’s performance is available memory—or more accurately, the lack of it. The updated system tends to use more space, and leftover files from the update may further reduce available storage, slowing down the device. For smooth operation, your iPhone needs a good amount of free space—ideally, 10-20% of your total storage. If iOS 18 is laggy on your iPhone, try to free up memory. But first, you need to figure out what’s taking up the most space.

1. Open Settings and tap General.
2. Select iPhone Storage.
3. At the top, you’ll see a storage graph showing how much space is used and how much is free.

If apps are taking up most of your storage, you’ve got a few options:

• If there are apps you don’t need anymore, delete them to free up the space they’re taking, with all their data.
• Offload unused apps. This removes the app itself but keeps its data, so you can reinstall it later without losing anything. To offload it just tap the app and select Offload the App.
• Some apps, especially messaging or social apps, let you clear their cache to free up space without deleting the app. Not every app offers this feature, though, and the settings might look different depending on the app. For example, as you can see in our snapshot, Telegram is taking up a lot of space. In this case, you can go to Settings > Data & Storage within the app and use the Clear Cache option to free up space without deleting your chats or important files.

Then there’s the Photos app, which holds all the photos and videos you’ve taken. If these files are taking up too much space, you can always go through your library and delete your least favorite photos. However, this can be incredibly time-consuming. Automating the process is a much better option, and we recently found an excellent tool for this: the free Clever Cleaner app for iPhone.

We tested it thoroughly and didn’t come across any paywalls, locked features, or even ads—a rare find these days. This app has features that outshine the native Photos app, for example, it can:

• Find Duplicate & Similar Photos. Unlike the native Photos app, which only identifies exact duplicates, Clever Cleaner uses AI to detect similar images. It finds photos that might look almost identical to the human eye but are actually different. The app groups these similar images together, so you can easily decide which ones to keep and which to delete.
• Identify Screenshots. Clever Cleaner can quickly locate and delete screenshots that often pile up and take up unnecessary space.
• Sort Heavy Files. The app can pinpoint large photos and videos that are eating up storage. This is especially useful for videos, as you can sort them by size from largest to smallest, to identify the biggest space hogs. It’s a handy feature that the native Photos app sadly lacks.
• Compress Live Photos. It can turn a Live Photo into a single still image, removing the extra frames and animations. This can save a lot of space.

Clever Cleaner is completely free to use, with no limitations, and the developer (CleverFiles) states on its official Clever Cleaner cleanup app page that it will stay free for anyone who downloads it now (and keeps it on their phone). We trust this, given that the developer is also behind the popular data recovery tool Disk Drill, which followed the same model back in the day. Here’s a great video where Clever Cleaner is put side by side with other iPhone storage-cleaning apps and compared in action.

But it’s not just apps and photos that can take up space. You should also check your Mail app. While plain text emails take up minimal space, attachments like PDFs, images, and other files can quietly accumulate over time. These files are often stored locally on your device, eating into your available storage.

If you’re using an older iPhone, System Data often ends up taking a huge chunk of storage. This is a common problem, and we have a detailed guide on how to clear System Data on your iPhone to help you reclaim that space.

Method 3: Update Problematic Apps

Outdated apps can cause performance issues after a major iOS update. Developers often release updates to provide compatibility with the latest version of the operating system. If your iPhone slows after iOS 18 update, check for app updates, especially apps that crash or take too long to load.

1. Open the App Store on your iPhone.
2. Tap on your profile icon in the upper-right corner of the screen.
3. Scroll down to see the updates that are scheduled to be updated. Click Update All or update individual apps that may be troubled.

When you update your apps, you’re guaranteed a seamless experience with iOS 18. If some apps still show poor performance even after updates, it could be due to deeper compatibility issues, which developers may address in future releases.

Method 4: Configure Keyboard Settings

If you notice input lag after the iOS 18 update, your keyboard settings could contribute to the problem. Features like keyboard predictions, haptics, or even third-party keyboards sometimes slow down your iPhone’s response time, especially in apps that rely heavily on text input.

1. Go to Settings on your iPhone.
2. Scroll down and tap General, then select Keyboard.
3. Turn off features like Predictive and Smart Punctuation to reduce processing overhead.
4. If you use a third-party keyboard, try switching back to the default iPhone keyboard to see if it improves performance.

When you adjust the keyboard settings, you reduce the load on the phone’s processor, which helps improve response time when typing. This fix often proves effective for those whose iOS 18 makes the phone slow and shows input delays, especially in messenger apps.

Method 5: Disable Dynamic Wallpapers

Dynamic wallpapers add visual effects to your home screen, but they also use more system resources. After the iOS 18 update, this feature can slow down your iPhone, especially on older devices. If iOS 18 is slowing down the phone’s visual effects, switching to a static wallpaper can improve it.

1. Open the Settings app on your iPhone.
2. Tap on Wallpaper.
3. Select Choose a New Wallpaper.
4. Scroll to the “Stills” section and select a static image.
5. Set it as your new wallpaper for the home screen, lock screen, or both.

After you disable dynamic wallpapers, you can free up system resources that your iPhone would otherwise use for animations.

Method 6: Reduce Interface Motion

The iOS 18 update includes various visual effects that improve the interface, but they also use additional processor power. Some users have reported that after updating to iOS 18, interface animations become “choppy” and experience occasional hangs. Reducing motion effects in the settings can help prevent these performance issues.

1. Go to Settings on your iPhone.
2. Tap on Accessibility, then select Motion.
3. Enable the option Reduce Motion.
4. Optionally, toggle off the Auto-Play Message Effects to further reduce animations.

Method 7: Turn Off the Background App Refresh

Background App Refresh allows apps to update their content in the background, even when you’re not using them. While convenient, this feature consumes system resources, which can slow down your iPhone. iOS 18 may slow down with background app updates enabled, especially after an update, as many apps use this feature to optimize their content for the new iOS version.

1. Open the Settings app on your iPhone.
2. Scroll down and tap on General, then select Background App Refresh.
3. Choose Off to disable Background App Refresh entirely, or select Wi-Fi if you prefer to limit it to Wi-Fi connections only.

Turn off Background App Refresh, so your iPhone can prioritize system functions instead of constantly performing background updates to app content. With this feature disabled, apps update when you open them, which may lead to a slightly slower startup, but it does not impact the overall performance of your iPhone.

Is It Possible to Downgrade iOS 18 to 17?

If your iPhone continues to experience performance issues after you update to iOS 18, you may consider a downgrade to iOS 17. However, once Apple ceases to sign an older version of iOS, a downgrade is no longer possible. Currently, Apple no longer signs iOS 17, so you cannot officially revert your iPhone to this previous version.

Apple limits version downgrades to maintain security and compatibility with new apps and features. While it might seem like a solution to revert to a more stable version, the system prevents this after the signing window closes. Downgrades through unofficial methods are risky and can lead to further issues, such as voided warranties and vulnerabilities introduced to your device.

Final Words

Before we conclude, we have to mention that battery performance can also make your iPhone feel sluggish. A degraded battery can lead to throttling and random slowdowns, so take a moment to check your battery health in Settings > Battery > Battery Health & Charging. If it’s below optimal levels, a battery replacement might be in order—or maybe it’s time to consider a new iPhone. After all, nothing lasts forever.

If you have more questions or run into obstacles, remember that there are plenty of online communities that can help. Forums like Reddit’s r/iPhone or Apple Support, or our own InsanelyMac iPhone Forum are great places to ask questions, share experiences, and find troubleshooting tips from other users.