I am helping out a friend with a slow WP. I installed hummingbird and it's telling me that some css files are slow to load (for example: https://cdnjs.cloudflare.com/ajax/libs/gsap/1.11.2/TweenMax.min.js - it takes 390ms to load). I would like to store this file locally and see if the performance improves. The problems is that I'm not sure about how to locate the file that is actually requesting this css file. Any help is appreciated.
I suggest a sweet plugin I use called String locator. It will search the whole site for a string like TweenMax.min.js. It will also search by plugin. When it find it it gives options to edit straight to the file. Hope this helps.