# Android slow after an update: why it happens and what to do

A phone is commonly slow for the first day or two after a system update because it re-optimises apps and rebuilds indexes in the background. If it is still slow after a week, look for apps the update changed or re-enabled, low storage and background activity.

## What is happening after an update

- Installed apps are recompiled and optimised for the new system version.
- Photo, file and search indexes are rebuilt.
- The Play Store updates apps to versions that suit the new release.
- Sync, backup and widgets catch up, and battery statistics start again.

## What to try first

1. Leave the phone plugged in on Wi-Fi overnight so background work can finish, then restart it once.
2. Check that the phone has free storage. A nearly full phone slows down badly.
3. Update your apps in the Play Store and install any second, smaller system update.
4. Restart in safe mode to see whether an installed app is the cause: if the phone is fast in safe mode, an app you installed is to blame.

## Find out what the update changed

Updates can add apps, re-enable ones you had disabled and change how much each app costs. The [slimdroid tool](https://slimdroid.com/app) can compare two scans and list new packages, re-enabled packages and cost that moved. You need an earlier scan from before the update; if you do not have one, scan now and again after the next change. Scans are saved in your browser, not uploaded.

## When it is something else

- Storage almost full: see [Android phone slow? Find what is slowing it down](https://slimdroid.com/guides/fix-slow-android-phone).
- The battery drains quickly as well: see [what is draining my Android battery](https://slimdroid.com/guides/android-battery-drain-apps).
- One app is slow: update it, clear its cache, or reinstall it.
- Still slow after a week: back up and, as a last resort, factory reset.

### How long is an Android phone slow after an update?

Usually a day or two while background optimisation finishes. If it is still slow after about a week, treat it as a real problem and investigate.

### Can an update re-enable apps I disabled?

A major update can re-enable or reinstall some disabled apps, so scan again afterwards and disable them again if you want them off.

### Should I factory reset after an update?

Not as a first step. Try the quick fixes, then compare scans. A reset is the last option because it removes your disabled-app changes along with everything else.

## Related guides

- [Android phone slow? Find what is slowing it down](https://slimdroid.com/guides/fix-slow-android-phone)
- [What is draining my Android battery?](https://slimdroid.com/guides/android-battery-drain-apps)
- [How to debloat an Android phone without root](https://slimdroid.com/guides/debloat-android-without-root)