IPS 3.4 has an option to deliver JS directly from google.

IPS 4 does not have this option.

Please, bring the canonical JS back for the most common JS files for our communities to take the advantage of the visitor's browser cache.

https://developers.google.com/speed/libraries/

Eh... the difference is pretty minor, and it only has an impact on the very first page load.

In 3.4 i had to disable the js coming from google. It was slower for my site.