If you truly wish to minimize memory consumption, I would change the list components to be application scoped.
It sounds like you're looking at very premature optimization, though, which is generally something to avoid. Unless they're very clearly large, unchanging lists, I wouldn't worry too much about the memory footprint.
Hi, Sean !
Thank you for the inspiring hints specially about my premature optimization concern. (That´s how things go when you´re an eager person !)