Even if Google used a separate highly optimised webserver for google.com/static/jquery.js, users who are logged in would be sending their auth cookies when requ

Even if Google used a separate highly optimised webserver for google.com/static/jquery.js, users who are logged in would be sending their auth cookies when requesting the library. Given that generally people have slower upload than download, shaving off a few bytes from requests is worth it. I also recall that browsers [used to (?)] limit concurrent requests per domain which this helps work around