How to Integrate Google Analytics (PageSpeed and Pageview both) for Ajax Loaded Pages?

I am having a web application which runs completely on Ajax Loaded pages (For fast browsing). I integrated Google Analytics but it's not tracking speed of my Ajax Requests. Can anyone please tell me how to track speed? So, that I can tweak my ajax loaded pages as per requirements.

I've seen some people were suggesting to use ga('send','pagespeed') but I don't know how to implement such ga requests because of low-quality documentations.