I’ve noticed a trend in recent years—a trend that I’ve admittedly been part of myself—where performance-minded developers will rebuild a site and then post a screenshot of their Lighthouse score on social media to show off how fast it is.
Mea culpa! I should post my CrUX reports too.
But I’m going to respectfully decline Phil’s advice to use any of the RUM analytics providers he recommends that require me to put another script element on my site. One third-party script is one third-party script too many.
Goodhart’s Law applied to Google’s core web vitals:
If developers start to focus solely on Core Web Vitals because it is important for SEO, then some folks will undoubtedly try to game the system.
Personally, my beef with core web vitals is that they introduce even more uneccessary initialisms (see, for example, Harry’s recent post where he uses CWV metrics like LCP, FID, and CLS—alongside TTFB and SI—to look at PLPs, PDPs, and SRPs. I mean, WTF?).
Ben shares the secret of SEO. Spoiler: the villain turns out to be Too Much JavaScript. Again.
Time to Interactive (TTI) is the most impactful metric to your performance score.
Therefore, to receive a high PageSpeed score, you will need a speedy TTI measurement.
At a high level, there are two significant factors that hugely influence TTI:
- The amount of JavaScript delivered to the page
- The run time of JavaScript tasks on the main thread
I hadn’t come across this before—run Lighthouse tests on your pages from six different locations around the world at once.
This is so useful! Get instant results from Google’s Chrome User Experience Report without having to wait (or pay) for BigQuery.
Here’s an example of my site’s metrics over the last few months, complete with nice charts.
“I am not a number, I am a free website!”
You don’t need Chrome to run Lighthouse.
With this bookmarklet you’re only ever one click away from the Lighthouse results for a page.