If a Time Machine backup takes longer than you expect

Your first backup might take a long time, depending on the number of files to back up.

How to get the best Time Machine performance

After the first Time Machine backup, future backups should be faster, because Time Machine backs up only the changes since your last backup. If most backups take longer than you expect, try these solutions.

Upgrade to macOS Big Sur

macOS Big Sur significantly improves Time Machine performance when used with an APFS-formatted backup disk. You get this benefit automatically after creating a new backup disk in Big Sur.

If you're backing up to the same disk that you were using before upgrading to Big Sur, follow these steps:

  1. Select your backup disk in the Finder.
  2. Choose File > Get Info from the menu bar, then look for the information labeled Format. 
  3. If the format isn't APFS, but you want improved Time Machine performance in Big Sur, use Disk Utility to erase the backup disk. This permanently deletes any backups and other data on that disk. 
  4. Set up Time Machine to use the backup disk again. After the first backup, future backups should be faster than before.

Check for large, frequently updated files

Some apps store data in unusually large, frequently updated files. Backing up such files can be time-consuming. Try these solutions:

  • Upgrade to macOS Big Sur and an APFS-formatted backup disk, as described above.
  • Or contact the app developer to learn how to best use their app with Time Machine. 
  • Or exclude those large files from your backup: Open Time Machine preferences, click Options, then click the add (+) button to add a file or folder to be excluded.

The Reduce Clutter feature of your Mac can help identify large files and show when they were last accessed.

Check for apps that keep your backup disk busy

Use your Time Machine backup disk only for Time Machine. Some apps, such as antivirus utilities, might keep your backup disk busy by frequently accessing the disk to find items or save items. Find out whether the app's settings can be changed prevent that.

Check your network performance

If you're using your Time Machine backup disk over a network, backup speed is affected by the performance of your network. If you're experiencing poor Wi-Fi performance, analyzing your wireless environment might help identify issues. You might get better performance by connecting the backup disk directly to your Mac.

Check your backup disk for issues

Time Machine should tell you when it can't complete a backup because of a problem with your backup disk, but you can use Disk Utility to check your disk for issues at any time. 

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