Here's a workaround that calmed it down for me. In Edit Preferences
Autocompletion, I deselected everything under my Exchange accounts,
restarted Evolution, and now it doesn't go thrashing every time I send
an email. It still goes ballistic when I switch to the Contacts tab,
but at least
I get the same behavior with Exchange when sending messages. It also
happens when I attempt to load an Exchange address list on the Contacts
screen. Perhaps it has to do with address resolution?
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gnome-keyring-daemon and Evolution cause 100% CPU usage
https://bugs.launchpad.net/bugs/236171
