I found that Mission Management has been accumulating “ghost” desktop areas in its inside database at ~/Library/Preferences/com.apple.areas.plist.
These orphaned entries are invisible however nonetheless iterated by WindowServer throughout house transitions, inflicting a CPU bottleneck.
Repair TL;DR
mv ~/Library/Preferences/com.apple.areas.plist ~/Desktop/spaces-backup.plist
Then log off / log in.
How you can Affirm
-
Rely saved areas (I had 19 however solely ever created 1 desktop per show):
defaults learn com.apple.areas | grep -c "ManagedSpaceID" -
Examine that quantity to the precise variety of seen Areas in Mission Management.
If the depend is way greater, the plist comprises ghosts.
Profiling (sudo spindump WindowServer -duration 3) throughout a swipe will present time spent in
managed_space_foreach_packages_space() and WSWindowActionGroupAddWindowAction() — each iterating over all saved areas.
Repair (Requires Logout)
Transfer the corrupted plist to its new backup location
mv ~/Library/Preferences/com.apple.areas.plist ~/Desktop/spaces-backup.plist
Log off, then log again in.
A full logout/login resets WindowServer’s inside house listing. Killing the Dock alone is inadequate.
After re-logging-in:
- House transitions return to full 120 FPS
- WindowServer CPU use drops to regular
- GPU resumes regular P-state habits
- My primary show’s desktop wallpaper had reset
Why It Occurs
com.apple.areas.plist can retain ManagedSpaceID entries for deleted or invalid Areas.
WindowServer nonetheless processes them, resulting in an O(n × m) price every body (n = areas, m = home windows).
Exterior shows set off a special compositor path that filters them, which is why the problem vanishes when a monitor is related.
