>> Cacheing. I get the superficial appeal of this. But there are dozens of popular Javascript CDNs available. What are the chances that your user has visited a

>> Cacheing. I get the superficial appeal of this. But there are dozens of popular Javascript CDNs available. What are the chances that your user has visited a site which uses the exact same CDN as your site? > Quite high - if you're using the Google CDN I'd imagine. Quite low in reality as there's no critical mass – most sites don't use the same versions of common resources. Google fonts is one of the better candidates for shared caching working but resources just don't live in the browser cache for very long (Facebook, Yahoo studies)