Hm. I don't know why that would make a difference!

One or more of the login applications interacted with launchd and somehow interfered with normal launching. Since removing most of the login items eliminated the problem and made restarting or logging in much faster, I did not go through the step-wise addition of individual apps to identify the culprit. It actually saves time to simplify the login process and launch the apps via a Keyboard Maestro macro after startup has completed.