Measuring Page Load Time of single-page app with GA

I'm using Google Analytics in an SPA. For any virtual page redirects (like an AJAX call to refresh the body of the page), I'm getting a page load time of 0ms. Is there a way to track how long that takes, just as if it was a full page refresh? I'm hoping to include how long it takes for the AJAX call and also the time to download and display images that are loaded as a result.