I didn't think Plus offered any performance boosts over the free license; that would be a pretty poor business strategy I think.
That being said, what exactly does the Plus license offer over the free license aside from support? What are the feature differences? Are there important directives available through Plus that are not available through free, which would make certain setups impossible?
I'm new to this whole server administration / setup thing, and have been wondering this recently as I try to set up a server.