Posting as an FYI incase others have this issue. Yesterday I upgraded the wife's computer to Catalina. Then had a heap of issues getting Photos to sync so she could get the photos of our recent holiday. Poked and prodded it for a day (e.g. created new photos library, logged in and out of iCloud etc) and couldn't get it to Sync at all. All throughout I noticed that accountd and secd processes where consuming heaps of CPU and throwing a bunch of console errors. I tried resetting permissions and a bunch of other things before eventually resetting the default keychain. (Keychain Access -> Preferences -> Reset my Default Keychains). This instantly fixed the problem CPU usage went back to normal and Sync'd a full 35000 item Photos Library in a couple of hours from iCloud.