I'm a webdev. I had to speed up web e-mail client, written in angular.js. Besides splitting huge request into couple smaller, async ones (huuge speed improvement) I've also switched downloading files from CDN to app server itself - that gives additional 4sec (sic!) shorter load time.
Can you explain how you achieved the 4 second difference using the webserver over the CDN? That seems orders of magnitude faster than I would have expected. I thought you would have been looking at 100ms one way or the other.