When page-load speed is the priority, is it better to use a minimal, lightweight javascript library (hosted on a CDN), or is it better to use something like jQuery, hosted on Google's CDN that the browser more than likely already has loaded?
Edit: What my question really boils down to is whether the cross-site caching effect of using jQuery hosted on Google's CDN outweighs the benefits of using an ultra-light library, also on a CDN.
jQuery is not heavy as compared to any other javascript library at present looking at the amount of features and browsers it supports.
You can consider this factor while selecting the plugins to be used on the page because they are written by various users and some may right it intelligently considering this factor or some may just right it for the sake.
Yes, if you use CDN like Google for jQuery it is most likely that the library must be cached by the browser and also Google has number of servers based on location so you don't have to worry about it.