Temporarily Disable Login Items in Mac OS X
Login Items are applications and helpers that launch immediately when a user logs in to Mac OS X. These are easily adjusted in system preferences, but you can also temporarily disable them on a per-boot and per-login basis.
To temporarily disable all login items and login apps from loading, hold down the Shift key when clicking the “login” button and continue holding until the desktop displays.
For Macs without a password set, you can hold the shift key after the initial grey Apple logo boot screen has passed. If you start holding Shift too early though, you will end up in Safe Mode instead.
Disabling Login Items were recently discussed as a means of speeding up boot time, using this temporary method will let you see the speed difference directly, before they’re disabled completely.
Thanks for the tip Dan