SafariBookmarksSyncAgent makes new iMac freeze

For the past few weeks my new iMac kept freezing. After many, many hours with Apple tech support, both in the store and on the phone, we narrowed it down to something called SafariBookmarksSyncAgent which is sucking up all my memory, putting the memory pressure into the red, then off the scale.

To use my computer, I have to keep the Activity Monitor up on the screen so I can force quit SafariBookmarksSyncAgent when it pops up every 3 to 5 seconds.

No one at tech support has been able to figure it out. We've tried safe mode, we've unchecked Safari (I use Firefox, not Safari as my browser) under iCloud in all devices in my house. The Apple tech people say they never even heard of SafariBookmarksSyncAgent. Right now, the engineering department is supposed to be looking into it.

How can I solve this issue?

I found a solution that worked for me. It involved updating the permissions for my home directory, as indicated in the following article:

https://support.apple.com/en-us/HT203538