If your iPhone is freezing, running sluggishly, or showing other performance issues after upgrading to iOS 26 (or after setting up a new device), you’re not alone. These problems are particularly common right after major updates, and many of the troubleshooting steps apply to iPads too.

What’s happening?

After installing a big iOS update or moving data to a new iPhone (for example a iPhone 17), your device typically performs extra background work — indexing files, re-optimizing content, etc. This can temporarily reduce battery life and make things feel less responsive. 
If it's been several days yet your device is still lagging, try the following fixes.

✅ 1. Update to the latest version of iOS 26

Make sure you’ve installed any minor patches that Apple released after the initial iOS 26 rollout. Bugs or performance issues from the original build can be fixed in newer updates. To check: Settings → General → Software Update. 

✅ 2. Disable Adaptive Power and Low Power Mode

In iOS 26, a new feature called Adaptive Power is enabled by default on some devices (for example newer iPhone 17 models). While it’s designed to extend battery life by reducing performance under certain conditions, it can also make the device seem sluggish. Similarly, traditional Low Power Mode throttles performance.
To adjust: Settings → Battery → Power Mode, and try turning off these modes if you see a performance drop. 

✅ 3. Confirm your internet connection is solid

Sometimes what seems like device lag is actually slow or unstable Wi-Fi or cellular connectivity. Many apps depend heavily on network access — so make sure your connection is reliable. If the network is weak, the app might appear hung or sluggish.

✅ 4. Update all your apps

If your apps haven’t been updated to match iOS 26 yet, one or more of them could misbehave and slow things down. Head to the App Store and install any pending updates.

✅ 5. Let your iPhone cool down

Smartphones reduce performance when they get too hot or too cold in order to protect hardware and battery. According to Apple, iPhones and iPads are designed to be used in ambient temperatures between 0 °C and 35 °C (32 °F to 95 °F). If your device feels hot (or you’ve just used it heavily after the update), move it to a moderate temperature and let it cool. 

✅ 6. Force-quit/reopen misbehaving apps

If a specific app is acting up (freezing, slow to respond), try force-closing it and reopening. That sometimes clears temporary glitches. 

✅ 7. Restart your iPhone

If you haven’t restarted your iPhone in a while, lingering temporary system issues may be causing slow behaviour. Simply rebooting the device can often restore normal responsiveness. 

✅ 8. Free up storage space

Performance drops, crashes or slowdowns can occur if your device’s free space is extremely low (for instance less than ~1 GB). Clear out unused apps, photos, videos, downloaded songs—anything you don’t need. After freeing up space, restart the device and see if performance improves.

✅ 9. Turn off Apple Intelligence

Some users on Apple’s support forums have reported that disabling the new “Apple Intelligence” feature in iOS 26 has helped restore smoother performance. You can disable it via Settings → Apple Intelligence & Siri.

✅ 10. Check the battery health / consider battery replacement

An old or degraded battery may not deliver peak performance, resulting in a slower device overall. Check your battery health (in Settings → Battery → Battery Health & Charging) and if it’s significantly degraded, consider getting it replaced