Silo: Exploiting JavaScript and DOM Storage for Faster Page Loads James Mickens Microsoft Research
[email protected] Abstract fast-loading pages result in happier users, longer visit times, and higher revenues for page owners. For exam- A modern web page contains many objects, and fetch- ple, when the e-commerce site Shopzilla reduced its av- ing these objects requires many network round trips— erage load time from 5 seconds to 1.5 seconds, it boosted establishing each HTTP connection requires a TCP page views by 25% and revenue by 10% [4]. Faster loads handshake, and each HTTP request/response pair re- also lead to more advertising impact, since Google’s Ad- quires at least one round trip. To decrease a page’s load Words system preferentially displays ads whose target time, designers try to minimize the number of HTTP re- pages load quickly [9]. Search engines also make load- quests needed to fetch the constituent objects. A com- ing speed a factor in their page rankings [22]. mon strategy is to inline the page’s JavaScript and CSS Given all of this, web designers have accumulated a files instead of using external links (and thus separate series of techniques for decreasing load times. Souder’s HTTP fetches). Unfortunately, browsers only cache ex- influential book High Performance Web Sites lists 14 of ternally named objects, so inlining trades fewer HTTP these techniques [23], with the most important one be- requests now for greater bandwidth consumption later if ing to minimize the number of HTTP requests needed a user revisits a page and must refetch uncacheable files.