“Analyzing your site using Page Speed or YSlow often produces lower scores than you might expect due to 3rd party resources with short cache times. 3rd party snippet owners use short cache times so that users receive updates in a timely fashion, even if this means slowing down the site owner’s page.
Stoyan and I were discussing this and wondered if there was a way to have longer cache times and update resources when necessary. We came up with a solution. It’s simple and reliable. Adopting this pattern will reduce unnecessary HTTP requests resulting in faster pages and happier users, as well as better Page Speed and YSlow scores…”