iPhone 13 lagging after iOS 26.3 update

Performance can slow down right after updating an iOS version because the system is re‑processing data in the background. This can affect YouTube quality, animations, and general responsiveness on your iPhone.

Try the following one at a time:

1. Open Settings ➡️ Wi‑Fi ➡️ your network ➡️ Forget This Network ➡️ then reconnect.

2. Open Settings ➡️ Apps ➡️ YouTube ➡️ Background App Refresh ➡️ turn off.

3. Open Settings ➡️ General ➡️ Transfer or Reset iPhone ➡️ Reset ➡️ Reset Network Settings.

4. Open Settings ➡️ Battery ➡️ check if any app is jumping to the top unexpectedly.

5. Restart the iPhone to reload system services.

Streaming quality and overall smoothness usually return to normal once the system finishes its background processing.

Axel Fl

iPhone 13 was released in 2021, over 5 years ago. Have you had the battery replaced in your phone yet? Batteries don't last forever and when a battery is failing, things don't work well. Open Settings > Battery > Battery Health - if the health is 80% or lower, the useful life of the battery has been spent and you need to schedule an appointment at your Apple Store Genius Bar and pay Apple to replace the battery --> https://support.apple.com/iphone/repair/battery-replacement

it is likely that after an iOS update, the system performs background processes to reindex files, features, and system data. Similar to macOS indexing, this helps ensure stability, optimize performance, and properly integrate newly updated components

update my iphone 16 to the new ios 26.4 and teh glithed and lagging is fixed, you can try

frannux wrote:

I am using an SE 2020 and it is draining my battery and then it shuts down. It has converted in a brick.

Same answer as I provided above, so read this:

Your phone is at or near 6 years old. Have you had the battery replaced in your phone yet? Batteries don't last forever and when a battery is failing, things don't work well. Open Settings > Battery > Battery Health - if the health is 80% or lower, the useful life of the battery has been spent and you need to schedule an appointment at your Apple Store Genius Bar and pay Apple to replace the battery --> https://support.apple.com/iphone/repair/battery-replacement

Updated my 13 pro max to 26.3.1 and this phone is terrible now. I’m talking extreme lag, my apps are not showing but they are there, failed calls etc. someone please check into this. My phone has more than enough memory so that’s totally not the issue. It’s a TB

I am using an SE 2020 and it is draining my battery and then it shuts down. It has converted in a brick.