Contacts: Slow showing large address books
I'm currently testing the latest development build (master/3.37.3) on Ubuntu 18.04 via Flatpak build from org.gnome.Evolution-master. Using a Dell XPS 15 with 6-core i7 and 32GB RAM.
I've imported over 150,000 contacts via CardDAV. The contacts are synced and can be browsed and searched. The email address autocomplete feature works fine when composing an email.
While searching for a contact from the Contacts tab can take up to 30 seconds, the GUI remains interactive. Subsequently clearing the search can take up to a minute, and the GUI is unresponsive while the contact list repopulates. Here's a graph of CPU usage during that time.
The unresponsive behavior can also be seen when starting Evolution and going to the Contacts tab. It occurs when the contact list is loading.