WordPress.org introduced a new delta updates system in WordPress 3.2 that downloads only files that have changed when updates are released, and with the release of 3.2.1 it has saved WordPress around 1 terabyte in bandwidth according to WPCandy.
As the code necessary for the partial updates was one of the new features in WordPress 3.2 (released earlier this month) it’s only now we’re hearing word of the impact it has had on WordPress.org’s costs.
The system is similar to that introduced in iOS 5, where new updates to the operating system include only changes — reducing the size of the download from between 600 and 700 megabytes to between 100 and 200 megabytes.
This system saves time for the user and bandwidth costs for the software developer. While the time-saving benefits are less applicable as WordPress updates take only seconds, saving a terabyte in bandwidth costs is a significant improvement.