A few years ago Brotli compression entered into the webperf spotlight with impressive gains of up to 25% over gzip compression. The algorithm was created by Google, who initially introduced it as a way to compress web fonts via the woff2 format. Later in 2015 it was released as a compression library to optimize the delivery of web content. Despite Brotli being a completely different format from Gzip, it was quickly supported by most modern web browsers.

Over the years it has been fun to track website page weight by comparing it to milestones such as the size of a floppy disk (1.44MB), the size of the original install size of DOOM (2.39MB) and when it hit 3MB last summer.

During a discussion about correlating 3rd party content to performance I decided to have some fun combining both the HTTP Archive and Chome User Experience Report data sets to see what we can learn. The results were pretty conclusive that there is a strong correlation between the % of 3rd party content on a site and the load times (measured via the onLoad metric).

Last week I wrote a blog post showing some examples of how you can use the Chrome User Experience report to compare your site’s RUM data to competitors. In this post I’d like to share some brief videos to help you quickly get started exploring the data via Google BigQuery.

For years Real User Measurement (RUM) has been the gold standard for how to measure the performance of web applications. And the reason for it is quite simple: there is no better measure for how users are experiencing your site, than the users’ actual experiences themselves.

Have you ever wondered why WebPageTest can sometimes show that a repeat view loaded with less bytes downloaded, while also triggering warnings related to browser caching? It can seem like the test is reporting an issue that does not exist, but in fact it’s often a sign of a more serious issue that should be investigated. Often the issue is not the lack of caching, but rather lack of control over how your content is cached.

Over the past few weeks the topic of security related HTTP headers has come up in numerous discussions – both with customers I work with as well as other colleagues that are trying to help improve the security posture of their customers. I’ve often felt that these headers were underutilized, and a quick test on Scott Helme’s excellent securityheaders.io site usually proves this to be true. I decided to take a deeper look at how these headers are being used on a large scale.

In January 2017, Facebook wrote about a new Cache-Control directive – immutable – which was designed to tell supported browsers not to attempt to revalidate an object on a normal reload during it’s freshness lifetime. Firefox 49 implemented it, while Chrome went ahead with a different approach by changing the behavior of the reload button. Additionally it seems that WebKit has also implemented the immutable directive since then.

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.