While this optimization tip won't speed up your computer or give you one-of-a-kind functionality when working with your iTunes library, it will go a long way toward making your playlists more manageable and functional.
As you add songs, videos and other media to your iTunes library, it can be all too easy to end up with duplicate files. Maybe you built a playlist for Monday morning workouts, and inadvertently built the same playlist months later for Friday workouts. The two identical playlists, with different names, could cause a little confusion when you're in a hurry and searching for the right songs to download to your iPod. It's not a major problem, but why put up with this kind of small hassle when it's easy to clean the duplicates out of your media library?
iTunes does include a "find duplicates" function, but it can be a bit clunky to use: You have to go through each file to determine whether it goes in the library or the trash bin. Applications such as Dupin (for Mac) not only identify the duplicate files, but also allow you to select how they manage them; you can program the applications to keep the most recently played version, for example [sources: Herrman, Adams].