Fix configd and systemuiserver high cpu problem

Just encounter a strange problem of high CPU from configd and SystemUIServer process in Catalina, which causes the fan boosting up and making enormous noises.

Manually killing these processes won’t help. And googling also doesn’t get much info.

Configd is the system configuration process, while SystemUIServer is the UI handling process. Apparently, something that needs to be configured goes wrong, and messes up with UI.

The culprit is the Finder connected with iPhone. Because iTunes is now gone, Finder is handling the sync with iPhone devices. But for some unknown reason, when my iPhone is connected thru USB, error “Could not check for an update to the carrier settings for your phone. This device is no longer connected” prompts. The Finder’s device tab of iPhone info still works, but the connection status will refresh constantly between success and USB error. Such constant updates lead to the CPU high usage.

Reset the finder settings plist file and force quit Finder works only for a while. Choosing the option to hide “CD, DVD & iOS devices” in the Finder sidebar preferences will be the solution. Update: one faulty USB port seems the actual reason.

The Finder’s device sync functionality is very buggy. Sometimes it will keep synchronizing thru WiFi and even prevent the system from restart. Make sure to uncheck the WiFi sync option in the connected device tab too.

Finally, the only way to sync/backup with iOS devices is thru iCloud.

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