If I were to implement an equivalent option, it would just store the song or setlist information as well as the page that was last viewed. Tapping the tab would just load that song/setlist and skip to that page. I would not leave things cached in memory for instant switching between tabs, as that would cause serious issues with memory usage on some devices. Would that stiil be sufficient for what you are wanting? Or are you envisioning being able to flip back and forth quickly between opened songs or setlists? I just don't think many tablets would have sufficient memory, especially tablets like the new Go tablets. The operating system also limits how much memory applications can use and doesn't like it when applications use too much (they get targeted to be eliminated in the background when multi-tasking).
Mike
Mike