2010 iMac was running slow, friend asks me to have a look - it's his wife's iMac. A bit of poking around reveals Console is going crazy with hundreds of copies of 'com.apple.iCloudHelper switching to keychain-db', various iCloud hammering going on, reports of dead ports (TCP or UDP ports, not eithernet ports) and so on. Looked in Keychain Access, found over 3200 duplicates of wife's iCloud password, over 1500 copies of iMessage password, and several hundred copies of various apple-related passwords in there. Deleting all but 2 copies of each (keep a copy each of the public/private pairs) has helped computer speed somewhat. Console is still spamming keychain messages and this feels like a temporary bandaid. Can anyone help me understand what's going on or fix it? 2010 iMac, fully updated, running Sierra 10.12.1, very few apps on it, only used for webmail, reading recipes on the internet and a few other things like booking holiday flights etc.