In order to speed up boot times, it's important go a bit deeper into the system on Macs in order to declutter them:
/System/Library/LaunchAgents/ Per-user agents provided by Mac OS X (usually left untouched)
/System/Library/LaunchDaemons/ System-wide daemons provided by Mac OS X (usually left untouched)
/Library/LaunchAgents/ Per-user agents provided by the administrator.
/Library/LaunchDaemons/ System-wide daemons provided by the administrator.
/Library/PrivilegedHelperTools/ authenticates startup and tools for non-AppStore apps
/Library/StartupItems/ System-wide startup items provided by the administrator.
~/Library/LaunchAgents/ Per-user agents provided by the user.
~/Library/StartupItems/ Per-user startup items (folder may not have been created if none present)
You may find more than a few items in these folders that are unneeded, possible carryovers from previous system migrations, possible crust from printer installs & external hard drive installers (HP and Seagate especially).
Also good to take a look at what is in your:
/Library/Application Support ~/Library/Application Scripts ~/Library/Application Support ~/Library/Preferences/
folders, if you’ve installed software then uninstalled it there is good chance that there are items left behind in these areas.
I finally tend to carefully clear out any redundant extensions for completeness:
/System/Library/Extensions
but if you go this far be very careful what you do.
