The article mentions that the HTTPS link to the resources is now default on Google's list of AJAX resources. I remember back in the day being warned that SSL connections have an appreciable overhead and so you should avoid SSL use unnecessarily. Is this no longer true? Has the overhead of https:// become negligible?
Yes it has become negligible. Google themselves have a nice talk about it. The major overhead is in the initial handshake. Google themselves have published how the major issues were in browser behavior (caching mostly) and not connection speed or cpu cost.
