Lately I've been getting beachballs and sluggish performance with Contacts on my Mac. I'm sure I'll be updating to Big Sur this Fall which will most likely take care of it, but, in the meantime, is it just a simple trashing of a pref file?
I'm now running Big Sur. Contacts have sped up a bit, but I'm having strange behaviour with it. Groups are being duplicated and most annoying, I attempt to create a new Group and it fails to be created. I also try to share Contacts via email and when trying to Send, all I keep getting is "in the process of being loaded." What a buggy one! I trashed the 3 files suggested here with no improvement. https://discussions.apple.com/docs/DOC-10581