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Lighthouse 8, Largest Contentful Paint highlights & great case studies

Jul 1, 2021

Hi there,

Last month, Google began its gradual rollout of new page experience metrics – primarily Core Web Vitals – as part of its search ranking algorithm. What does this mean for most site owners? It's still too early to say. According to Google: 

"Page experience won't play its full role... until the end of August. You can think of it as if you're adding a flavoring to a food you're preparing. Rather than add the flavor all at once into the mix, we'll be slowly adding it all over this time period.” 

We've been busy adding our own flavor – most recently, by highlighting Largest Contentful Paint (LCP) events in your charts. (Scroll down to learn more about this.) And it's been exciting to see other folks in our industry add flavors of their own in the form of Vitals-related research and case studies, which I've included below.

As always, I welcome your feedback and suggestions. If you're doing anything exciting in the web performance space, I'd love to hear about it!

Until next time,

Welcome to the team, Andy!

I've always felt so incredibly lucky that I get to work with such an amazing team at SpeedCurve. Now that Andy Davies (@AndyDavies) – one of the best consultants in our industry, whom I've known for years and years – has joined us, I feel even luckier! Among (many) other things, Andy will be helping us build self-serve performance consultancy into our tools. He'll also be available for in-depth consulting when you and your own team need extra support.

NEW! Largest Contentful Paint (LCP) highlights

As you focus on measuring Largest Contentful Paint as part of your Core Web Vitals tracking, you may find yourself wondering what the heck your largest painted elements actually are. We've made LCP events easy to spot by highlighting them in your Vitals dashboard, your test details, and your Sites dashboard, where you'll also see how key metrics are trending over time.

Some other Web Vitals features and research you might want to check out:

NEW! Run synthetic tests with Chrome Canary

If you care about measuring how upcoming browser changes can affect the performance of your pages – for better or for worse – you can now run Synthetic performance tests using Chrome Beta and Chrome Canary

NEW! Lighthouse 8 update

We've updated Lighthouse from 7.5.0 to 8.0.0. Here's a summary of what's changed and the impact you can expect to see on your metrics.

The biggest changes are:

  • the weighting of metrics used for calculating the performance score, and
  • the adoption of the recently updated Cumulative Layout Shift (CLS) calculation.

Google anticipates the majority of sites could see improvements to their scores. Our own research here at SpeedCurve suggests that there will be a moderate increase of the performance score (1-5 points) for most sites. Sites that had a high CLS score and/or TBT were penalized more heavily due to the weighting changes and saw a decrease in the score which was sometimes significant (5-10 points).

ICYMI: Bookmark & compare synthetic tests

This is one of my all-time favourite SpeedCurve features – and that's saying a lot! We've made it super easy to compare any two synthetic tests, including side-by-side comparison charts that let you not only spot regressions, but pinpoint what caused them. Being able to identify things like which requests got bigger/smaller and quickly spot problematic new resources – so incredibly helpful.

More good reads from the #webperf community: