The winlogon notification subscriber <Profiles> took nnn second(s) to handle the notification event (Logon).
After 2 days of disabling everything in my single GPO of Comp Config, and re-enbaling everything one bit at a time, I discovered just now that disabling "Run logon scripts synchronouslyâ€ cured my problem!
No more Event IDs 6005 and 6006! Hurrah!
This is found under Computer Configuration\Policies\Administrative Templates\System\Scripts