This is what I do to make my iChat start up really really fast and smooth.
I really hate opening iChat and waiting for all my buddies to start *fading* onto the list... it takes forever sometimes... *woosh woosh woosh woosh* ... and so on.
This is my work around... and it works like a charm.
Turn on iChat's status menu in the menu bar.
Then click it and choose "Available"
Your buddies appear instantly (no wooshing)
Then either click "Buddy List" or launch iChat.
iChat will come right up and have the Buddy List available for you in the blink of an eye.
It's not difficult and it's a great way to see who's online before you decide to launch iChat.