macOS processes › Core system
What is cfprefsd on Mac?
cfprefsd manages app and system preferences on your Mac. Apps read and save their settings through it instead of touching their preference files directly.
What it does
Settings live in .plist files in Library/Preferences folders. cfprefsd keeps them in memory, hands them to apps quickly, and writes changes back to disk. One copy runs for the system and one for each user, plus a few for macOS service accounts, so several copies are normal.
Why it gets busy
- An app reading or writing its settings in a loop, usually because of a bug.
- Many apps launching at once, each loading its preferences.
- An app that stores unusually large amounts of data in its preferences, which makes every save slow.
Why is cfprefsd using so much CPU?
cfprefsd uses CPU when an app reads or writes its settings far too often. Quit apps one by one to find it, then update that app.
Is it safe to quit?
macOS starts it again right away. A setting an app changed a moment earlier may not have been saved yet.
How to calm it down
- Quit apps one at a time and watch cfprefsd in Activity Monitor to find the one hammering it.
- Update or reinstall that app, and tell the developer if it keeps happening.
- Restart your Mac to clear a stuck state.
In SystemWatch
SystemWatch's History shows whether cfprefsd's busy periods start when a particular app opens, and that app is usually the one to update.
