macOS processes › Menu bar and interface
What is SystemUIServer on Mac?
SystemUIServer runs some menu bar items, mostly older-style ones such as certain third-party menu extras. Most of Apple's own menu bar items moved to Control Center in macOS Big Sur.
What it does
It hosts menu extras, small menu bar items that plug into it instead of running as separate apps. Menu extras of this kind are rare now; most menu bar apps run as their own processes. It runs all the time and is normally light.
Why it gets busy
- An older menu extra that updates constantly or has a bug.
- Memory that builds up over weeks of uptime.
Why is SystemUIServer using so much CPU?
SystemUIServer runs some menu bar items. A misbehaving menu extra can keep it busy, and restarting it is safe and quick.
Is it safe to quit?
macOS restarts it immediately. The affected menu bar items disappear for a moment and come back.
How to calm it down
- Restart it with
killall SystemUIServerin Terminal, or quit it in Activity Monitor. - Remove menu bar items you don't need: hold Command and drag the item out of the menu bar.
In SystemWatch
SystemWatch knows SystemUIServer's normal memory use, so it can tell you when a restart is likely to help.
