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I haven't looked in details at the 3 other approaches but I know that a big difference between what I do in Shelves and what I've seen done in other places is how user interaction is handled. Shelves listens to scroll events on the ListView and tries to identify taps vs scrolls vs fling to always give priority to the UI. For instance, when you touch the screen to stop a fling, Shelves starts loading images, but does so only after a very short delay so that if you are touching the screen to fling some more, the fling animation won't stutter because of the extra work load. But that's details.