Diffable: only download the deltas
Josh and James work on Google Maps which has a main script that is ~300K. A typical revision for this 300K script produces patches that are less than 20K. It’s wasteful to download that other 280K if the user has the old revision in their cache. That’s the inspiration for Diffable.
The savings are significant. Using Diffable has reduced page load times in Google Maps by more than 1200 milliseconds (~25%). Note that this benefit only affects users that have an older version of the script in cache. For Google Maps that’s 20-25% of users.