macOS Contacts ( contactsd ) daemon burning hours of CPU and reading gigabytes of data from disk

To even further reduce the residual CPU consumption of the contactsd daemon, I had to disable Siri Suggestions. I noticed that suggestd and contactsd were still burning CPU together. When I disabled Siri Suggestions and rebooted, contactsd CPU usage fell to almost nothing. Settings --> Siri Suggestions, toggle to off position. And on a related note, if you happen to see photoanalysisd burning CPU at the same time as contactsd, you might try going into Apple Photos (View --> Photos --> People) and deleting any people that Apple Photos may have tagged. I believe that photoanalysisd and contactsd can burn a lot of CPU time trying to match faces of people in Apple Photos with people in Apple Contacts. If searching by people's names in Apple Photos is not important to you, it might help to delete any existing photos that Apple Photos is searching through to match with faces in Apple Contacts.

SOLVED. (At least for me) Over the weekend, I moved all 8,000 of my contacts from Google Contacts back to iCloud Contacts. macOS CPU and disk usage has dramatically reduced to the point of not being an issue any longer. Also, the issue of starting to create a new contact in Apple Contacts and having the window close prematurely is now gone. I really hope Apple can work with Google Contacts to figure out how to make macOS Contacts and Google Contacts work together.