Mac OS X: If Terminal is loading slowly on your Mac (for me, slow loading in terminal is more than five seconds), try clearing out the ASL logs.
For reasons I do not understand, ASL logs make Terminal load really, really slowly. You can clear out the ASL logs by executing this command:
sudo rm -f /private/var/log/asl/*.asl
Before executing that command, though, make sure you don't need those logs. Because that line will effectively delete all of them.
I put that in my .bash_profile as a function because Terminal.app is often slow for me.
I gave it a try on a machine where Terminal's been extremely slow for me and it did seem to help a lot, but likewise, I'm not sure why. A little research also shows the folks at OS X Daily had similar results. If you've got a better explanation, let's hear it in the comments.