On Nov 14th, Mozilla released Firefox Quantum. On launch day, I personally felt that the new version was rendering pages faster and I heard anecdotal reports indicating the same. There have also been a few benchmarks which seem to show that this latest Firefox version is getting content to screens faster than its predecessor. But I wanted to try a different approach to measurement.

Since the HTTP Archive is capturing the timing information on each request, I thought it would be interesting to correlate request timings (ie, when an object was loaded) with page timings. The idea is that we can categorize resources that were loaded before or after and event.

I thought it would be interesting to explore how some of the page metrics we use to analyze web performance compare with each other. In the HTTP Archive “pages” table, metrics such as TTFB, renderStart, VisuallyComplete, onLoad and fullyLoaded are tracked. And recently some of the newer metrics such as Time to Interactive, First Meaningful Paint, First Contentful paint, etc exist in the HAR file tables.

As of July 2017, the “average” page weight is 3MB. @Tammy wrote an excellent blog post about HTTP Archive page stats and trends. Last year @igrigorik published an analysis on page weight using CDF plots. And of course, we can view the trends over time on the HTTP Archive trends page. Since this is all based on HTTP Archive data, I thought I’d start a thread here to continue the discussion on how to gauge the increase in page weight over time.

One of the exciting new features in Chrome Dev Tools is the addition of 3rd party product names integrated into Dev Tools. I was interested in exploring how this works, and whether any of this data can be used to do further research via the HTTP Archive.

I was curious to see where Server-Timing was implemented on the web, so I started searching the HTTP Archive for sites using it. Interestingly enough, there were no sites in the HTTP Archive that had Server-Timing response headers before 3/1/2017. Since then it’s usage has been gradually increasing each month. As of July 2017, there are 72 sites and 352 HTTP responses containing Server-Timing headers.

I worked on an interesting performance investigation recently, and I wanted to share some of the techniques I used to dig in and isolate the problem.