domInteractive: When the browser has parsed the main HTML document.
firstPaint: The moment something is first painted on the screen (currently only collected in Chrome and IE/Edge).
loadEventEnd: When the load event fired in the browser and the current document is complete.
responseStart: The time it takes for the client to receive a response from the server (TTFB).
saveTiming: The time it takes to submit and save an edit on an article.
