Why Is My iPhone Slow? What to Check Before You Replace It

An iPhone that has gone slow is frustrating, and it is easy to assume the only fix is a new one. Often it is not. There are a handful of common causes, and most cost nothing to check.

Start with a restart

A restart is quick and harmless, so it is a good first step. If the iPhone is only a bit sluggish, a restart sometimes clears it.

Give it time after an update

If the slowness started just after a software update, including iOS 27, this may be normal. After a software update, your iPhone rebuilds the information used by Search and Siri. This can take hours or even days, depending on how much data is on the phone.

It finishes more quickly when the iPhone is not in use, connected to power and on Wi-Fi.

Check your connection

Sometimes the iPhone is fine and the connection is the problem. Slow performance can come from network congestion, or from the phone reconnecting to mobile towers while you move around.

If an app or a website is the only thing that feels slow, try Wi-Fi, or try a different location. If mobile data is slow in several places, the problem may be with the mobile service rather than the iPhone.

Do not force close your apps

This one runs against old habit. Force closing apps unnecessarily can slow your device down, because reopening an app takes longer when it has to load all its data again.

Closing an app is useful when it has stopped responding. Swiping every app away each night is not.

Check your storage

A nearly full iPhone is one of the most common causes of slowness. iOS manages storage automatically when you install and update apps, but to avoid slowdowns you should keep at least 1GB of space free.

Go to Settings, tap General, then tap iPhone Storage. You will see recommendations and a list of apps with the space they use. Photos and videos, messages and attachments, downloaded videos, files and apps are the usual big users.

For each app, Apple gives you two choices. Offload removes the app but keeps its documents and data. Delete removes the app and its related data. You can also turn on Offload Unused Apps, which lets the iPhone remove apps you do not use when storage is low. That setting is under Settings, Apps, App Store.

If you are about to delete photos, make sure they are backed up first. Our guide to backing up an iPhone or iPad explains how.

Turn off Low Power Mode

Low Power Mode saves battery, but it does so by holding the iPhone back. It reduces background activity, turns off some visual effects and pauses things such as iCloud Photos and automatic downloads. The battery icon turns yellow while it is on.

If your iPhone feels slow and the battery icon is yellow, turn it off. On iPhone 15 and later, go to Settings, tap Battery, then tap Power Mode. On iPhone 14 and earlier, go to Settings, tap Battery, and use the Low Power Mode switch. It turns off automatically once you charge to 80% or more.

Heat, cold and the battery

An iPhone that gets too hot or too cold might run slower. If yours has been in a hot car or in direct sun, let it return to a normal temperature before you judge it.

Batteries wear out. As a lithium-ion battery ages, it holds less charge, and its ability to deliver maximum instant power can also drop. This ability can also fall temporarily when the battery is low or cold.

To see where yours stands, go to Settings, tap Battery, then tap Battery Health. iOS can show the battery’s health and recommend a replacement when one is needed. Our guide to battery health and charge limits covers what the numbers mean.

If the battery turns out to be the problem, it is worth getting a price for a replacement before you buy a new phone.

Need a hand?

If your iPhone is still slow after these checks, we can look at it with you. See our Mac and Apple device setup and troubleshooting service, or contact Your Mac Tech.