iPhone lagging after iOS 18 Update

I’m experiencing this too, and I found this article with a suggestion that worked: https://www.idownloadblog.com/2023/04/07/how-to-fix-slow-search-on-iphone/

Toggle Search off and on

1. Go to iPhone Settings and tap Siri & Search.
2. Scroll down and turn off all the switches you see in the screenshot below.
3. Restart your iPhone.
4. Go back to Siri & Search settingsand turn on the switches. After this, Spotlight Search should work as intended.

This makes sense that it works because after an OS update, Siri updates its search index for your phone messages, mail, and apps. It can take a long time and while it’s working in the background, apps slow down and searching can take longer than usual, and you might notice Photos.app says that it’s not syncing to iCloud because it is “optimizing system performance.” To help it along, I also made sure to turn off low power mode and plug in my phone so that the phone can run these long tasks as quickly as possible. 

THIS WORKED PERFECTLY!!

I read through this entire discussion post and this was the first solution I tried and it was easy and it worked.

The search and Siri settings pages have been separated in iOS18, so I just toggled everything off from both settings pages. Then, I powered off my phone and let it rest for a couple minutes. Powered back on, turned all the settings back on, and ALL ISSUES have gone away…

Note: your phone might lag a little bit while starting up again, make sure to close all tabs and let the software boot up

EDIT: I realized the reply function doesn’t really work so the original post I was quoting does not show. I mostly outlined the process of fixing the iOS18 lag issues, but if this explanation isn’t clear just find an earlier post of someone talking about search and Siri steps.

Adjusting Siri and search settings and following other suggestions from this article: 9 Steps to Fix an iPhone That's Lagging and Slow After the iOS 18 Update fixed my lagging issue. I hope this helps. 

I had the same issue after my iPhone updated to 18 last night. I shut my phone completely off for a few minutes. After I restarted, the issue seems to be resolved.

Nothing helped and i had the same lagginess, especially when typing on discord, the text appeared with almost half second delay. I tried some solutions proposed in this thread and it didn't work, until I tried the "reset keyboard dictionary" - IT WORKED!

Thanks a lot for the tip :)

The latest update 18.1 that I installed today 01-Nov-24 has fixed the main issue I had with Notes being extremely slow. And it seems to have helped most slowness on the phone (iPhone 15 pro max)

I was having the same issue for long time... After I turned off low power mode it became bit better.

I updated my phone to 18.1 Shute it down and reset and now it works beautifully

I updated my iPhone 15 pro max to iOS 18.1 and did a shutdown and reset it and now my iPhone is back to working beautifully again

I had that exact problem before I upgraded to iOS 18.1 shut down and reset and now my phone is fine

Had the same problem..

got it fixed.

turn off private relay in iCloud and the problem got solved

Closing down most of the 50+ apps I found were running in the background seems to have helped me

Binsont4tooth wrote:

After today’s update, I’m facing immense lagging issue with the UI, while playing games ( graphics as Average) and typing pauses. System had utilised only 50% storage. What’s the suggested solutions?

[Re-Titled by Moderator]

Restart, Reset, Restore from backup and Restore as NEW.

Since you mentioned your browser is sluggish, try clearing the cache and data—it can make a big difference. Also, make sure all your apps are up to date. For the keyboard lag, they suggest keeping only one and removing any others you might have installed.Hope this works for you!

[Edited by Moderator]

This again?

See 255623013 about the excessive battery consumption as a result of the iOS 17.6.1 update.

First, understand that the software does housekeeping after an update. It can usually be accomplished overnight but that depends on your device and its data. Try to install updates overnight and leave the device on the charger (It’s ok to do so and won’t ruin the battery. That rule applied to older battery technology). This is so that processor intensive tasks like file indexing for Spotlight Search or iCloud syncing can occur then and not during your day.

It's not "lagging" and "slow". It's just invisibly super busy for a while, after the update.

That's my theory anyway.