When the game first starts, it has to check the add-ons to make sure they aren't crap-ons. The reason it has to do it so soon is because of client add-ons. Client add-ons start right after all the client code is executed.
If you don't have a lot of add-ons, then I'm not sure what the problem is. I have a crap computer and mine starts up in a decent time.