What is trustd?
trustd decides whether certificates can be trusted. Every secure (HTTPS) connection and every signed app or update relies on a certificate, and trustd checks that it's valid, not expired and issued by someone your Mac trusts.
Results are cached, so it's normally quiet. Bursts happen when many new connections or apps need checking at once.
Why is trustd using so much CPU?
- Lots of new secure connections, such as a browser restoring many tabs, or a sync starting.
- Installing or updating many apps, each with signatures to check.
- Network problems, when certificate checks time out and retry.
- Security or VPN software that inspects network traffic.
How to fix high trustd CPU usage
- Confirm it in Activity Monitor. Press ⌘ Space, type Activity Monitor, open the CPU tab and sort by % CPU. Watch
trustdfor a minute: short spikes are normal, only steady high usage needs fixing. - Give it a few minutes after login, updates or opening many tabs.
- Check your network. A flaky connection or captive Wi-Fi portal can make checks retry.
- Update or pause VPN and security software to see if it's the trigger.
- Restart if it stays busy with nothing new happening.
More help: How to check CPU usage on a Mac