macOS processes › iCloud and sync
What is biomesyncd on Mac?
biomesyncd syncs Biome data, the record of app and device activity macOS uses for suggestions and personalization, between your Apple devices.
What it does
macOS keeps on-device streams of activity, called Biome, that features like Siri Suggestions learn from. biomesyncd shares them with your other devices, both directly with nearby devices and over the network, and maintains its database. Its launch settings schedule a sync about once an hour when a network is available, and a daily database cleanup that runs only on power.
Why it gets busy
- Catching up after one of your devices has been offline for a while.
- Adding a new device to your Apple Account.
- Its daily database maintenance.
Why is biomesyncd using so much CPU?
biomesyncd syncs on-device activity data between your Apple devices about once an hour. A long catch-up sync can show up as high CPU and settles on its own.
Is it safe to quit?
macOS starts it again for its next scheduled run.
How to calm it down
- Let it finish. Most runs are short.
- If a run lasts for hours, restart the Mac. The next hourly sync starts clean.
In SystemWatch
SystemWatch's History makes biomesyncd's hourly rhythm visible, so you can tell a normal sync run from one that's stuck.
