No. First of all, the YUI data is served from yahooapis.net, not yahoo.com. Second, every effort is made to keep the request as small as possible, and cached

No. First of all, the YUI data is served from yahooapis.net, not yahoo.com. Second, every effort is made to keep the request as small as possible, and cached for as long as possible. 1. A cookie would be a waste of bytes. 2. Since the headers instruct your browser to cache it for 10 years, it's quite likely that you won't even hit their server on the second page that uses this file. Don't believe me? Check for yourself: curl -I http://yui.yahooapis.com/2.6.0/build/yahoo/yahoo-min.js