The Constant Whirring
Time Machine is macOS’s robust, built-in backup solution. When you connect an external hard drive and designate it as a backup disk, Time Machine defaults to a highly aggressive schedule: it automatically attempts to create an incremental backup every single hour. While this guarantees you will rarely lose more than 60 minutes of work, it also means your external hard drive is constantly spinning up, writing data, and consuming system resources. If you are working on a battery-constrained MacBook or rendering a heavy video project, this hourly background activity can significantly throttle your performance.
Scheduling Manual Backups
To reclaim your system resources and stop macOS from automatically backing up to Time Machine every hour, you must change the backup frequency or switch to entirely manual backups.
Click the Apple logo in the top-left corner of your screen and select System Settings. In the left-hand navigation sidebar, scroll down and click on General. In the main right-hand panel, click on Time Machine. You will see a list of your configured backup disks. Look for the dropdown menu labelled Backup Frequency. By default, this is set to “Automatically Every Hour.” Click this dropdown menu. If you want less frequent automatic backups, you can select “Every Day” or “Every Week.” To completely stop the automated process, select Manually. From now on, Time Machine will only back up your data when you explicitly click the Time Machine icon in the top menu bar and select “Back Up Now.”