Mac mini sharing triggers heavy background CPU use on Tahoe
On an running 25.5.2, enabling sharing caused to keep using about 63.8% of the CPU. The otherwise idle machine also showed using about 17.4%. Removing every and every user allowed to share did not reduce the load.
Turning sharing off brought down to 0%. Turning it back on and sharing only a new tmp folder inside the brought the high usage back. No problematic was found.
The logs showed CFOpenDirectory repeatedly opening account and sharing information and retrieving its details at a very fast rate. The exact cause remains unknown, but the checks point toward an interaction between sharing and the system's directory lookups rather than one particular folder or user.
Key points
- used about 63.8% of the CPU while sharing was enabled.
- Removing all s and allowed users did not lower the load.
- Disabling sharing reduced usage to 0%.
- Sharing only one new tmp folder caused the high usage to return.
- used about 17.4% and repeatedly requested directory information.