How to fix problems with iCloud and iCloud Drive
When should you turn iCloud off to try to solve syncing problems? What use is a Content Caching server? What tools can help diagnose and fix problems?
brctl
Diagnosing iCloud problems using brctl, sync budgets and throttles
How much help does macOS provide for the diagnosis of iCloud problems? What does iCloud ‘throttle’, and what are its ‘budgets’?