Makes the site load faster =)

I can't find a write-up about it now, but last time I dug in to it they were pulling a really clever trick where their pages were served with a very light chunk of HTML (just enough to layout the page) followed by a sequence of script blocks that populated different areas. The magic is that the script blocks came back in the order in which the relevant back-end services replied - so if the timeline service replied instantly, the timeline would be rendered first - then as other services (notifications, app list, etc) finished new script blocks would be written out in to the HTTP stream already open to the browser and that content would appear.

This works amazingly well across all browsers, because the original browsers from the 1990s were designed with modems in mind and had to progressively render the page as it loaded. It turns out you can use that ability to serve a stream of script blocks to a page and dramatically reduce time-to-content-visibility.