How do you enable/disable startup items in OSX? Powermacs had extension manager where you could choose which extensions to load at startup. You could even create boot profiles and choose one depending on what you wanted to do with your computer. When I use my computer day to day, I have various helpful little apps that start at bootup Little snitch firewall, iStat menus, iSync etc. But sometimes, I need to squeeze every drop performance out of my computer, so I don't want unnecessary memory-resident programs running in the background. If you force-quit them, they just start up again. How are startup items defined in MacOS? Is there some kind of pref file or script?