How do Sports Illustrated's Gallery Pages Load So Fast?

I've been taking a look at their code and I can't quite figure it out. Are they loading entire new pages, or are they using jquery 开发者_运维百科to change the browser url and keep most of the page static?

I'm viewing source of this page.

I don't think there is a "silver bullet" explanation--their site is likely fast because they've performance-tuned it and removed any significant bottlenecks.

They are in-fact reloading the page with each selected image--this is clear with a HTTP debugger such as Fiddler2.

The perceived speed is partly explained by their use of content-delivery-networks and gzip compression--both speed up delivery of content. Their HTML structure likely factors is as well, and there is the chance they are streaming the response to allow the browser to begin rendering as early as possible.