Excess CPU/Energy use with iCloud account in Apple Mail.
There is huge CPU and energy use with the iCloud account in Apple Mail (MacBook Pro, Catalina 10.15.6) – it's associated with a continuous "Moving messages" progress bar showing in the Mail Activity window.
This doesn't occur with the two other Exchange accounts I use, and it disappears if I disable or take the iCloud mailbox offline.
In addition, the iCloud account on my Mac does not synchronize properly with iCloud. iPhone Mail seems to work properly.
Anyone have an explanation/solution for this?
(Before you ask, I've checked the disk with Disk Utility, tried starting in Safe mode, restarting, cleaned up some extraneous folders in the iCloud account, and a variety of other manoeuvres.)
MacBook Pro 15″, 10.15