Lots of people have this problem and have continued to have it for a long time.
I have hits on Apple discussion and on the wider internet going back years and there are still many on Discussions and on Google.
I've repeatedly tried every one of the suggestions:
-- upgrading to new OS over at least five generations and keeping it up to date automatically
-- having plenty of RAM per the Activity Monitor,
-- local storage over 10% free (formerly on hard drives, for years now solid-state storage),
-- a 750 MB/sec hard-wired internet service,
-- 1+ terabyte of iCloud storage out of our 2-Terabyte plan,
-- exporting and re-importing the contacts (which means reconstructing every item in the smart list).
This never happens on my iPhone when I update a contact.
Anecdotally, cutting my Macbook off of internet service and my own network, which I do occasionally when the problem is urgent seems to allow me to edit contacts at normal speed, without beachball hangs.
But it is hard to be sure that the problem didn't subside on its own by the time I went to Networks to cut myself off.
This suggests that Apple could fix the Contacts.App software so that when the system starts trying to sync to the iCloud or my other devices it is paused by my typing to edit a contact.
Why would that be hard to do?