I think a lot of users have this experience. I for one, happen to experience it the earliest among my friends. Though I’d changed to Google Chrome months ago, but Chrome is getting unstable for my usage, and I love how FireBug plugin works in Firefox and all the rest plugin from Firefox. The list would go whole day just like sales training session. That’s why I’m still convince that Firefox gonna take over the browser share soon 
Firefox preloader is a little application that helps load Firefox easier on first load. Firefox preloader load a little memory when you first boot up your computer, to help smooth fresh loading of Firefox. What I experiences without this preloader was a lagging session for at least 3 minutes everytime. Though there are tips on how to speed up Firefox, but it limited the whole usage of Firefox! I understand that bookmarks is one of the factor of speed loading, but I need those bookmarks 
However, I don’t see Mac version though….