Gate One already does this (though it sends whole files not just the diffs). Once a client has an asset (JS, CSS) there's no reason for it to be re-downloaded

Gate One already does this (though it sends whole files not just the diffs). Once a client has an asset (JS, CSS) there's no reason for it to be re-downloaded unless there's a change. Another improvement in Gate One's implementation is that it uses IndexedDB instead of localStorage. This is significantly more performant--especially as you add more/larger assets (localStorage blocks--always--whenever it is used). It also downloads all assets over the WebSocket connection which has significantly improved performance over multiple GET requests. It's quite fast.