tuples

This addresses one of the major factors related to AJAX speed: data transfer. Although hashes, associative arrays, objects and XML are easy to read, they introduce overhead for the keys/tags. This minimizes transfer by relying on ordered arrays and cooperative caching that only sends that data that the script needs.

This is an unnecessary replacement for autocomplete options that contain very little content (e.g., user names and node titles), but it does yield performance benefits when using it for autocomplete on larger content blocks (in terms of total markup).