I need the BEST configuration...PLEASE!!!

ok I have ALL of my media on a External NAS...a Westen Digital My World II to be exact. I access itunes from several computers. my laptop, my wifes laptop, and a computer that stays on all the time just so that I can have itunes always up for the ATV3. My itunes is SOOOO SLOOOW and I have been reading so many different ways to configure the system that I don't know what to do. some people say to have th elibrary and .xml files on each local machine. some people say keep it on the NAS. All I want to do is be able to have separate playlist then my wife but be able to edit and/or update the library from any of my computers. is that too much to ask?