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Web Vitals updates, sampling RUM & the fastest and slowest US retail sites

Jul 1, 2022


Hi there,

Last month I attended Smashing Conference in San Francisco. It was my first in-person event in a couple of years, and in addition to being inspired by the fantastic speakers and conversations I enjoyed, it was wonderful to experience the joy of being present with hundreds of other people.

One of my biggest takeaways from the conference was a renewed sense of the journey that we're all on when it comes to learning about the web and how we build and maintain our own small parts of it. I realized that, while we might be domain experts in our own niches, we all have so much to learn and appreciate about myriad other niches.

If you're relatively new to web performance, hello! I hope you find the articles in this newsletter helpful. I'd love to hear back from you. What are the biggest performance-related questions on your mind? What would help you most as you continue your performance journey?

If you're a performance old-timer (like me, I guess), hello to you, too! One of the exciting things about our industry is that we're constantly evolving and refining what we do. This month's newsletter explores new metrics and analyzes old assumptions. I'd love to hear your thoughts.

Until next time, I hope you stay safe, happy, and well.



NEW! Change the summary metrics on your charts

You may have noticed that we recently added a new display option that lets you change the summary metrics shown at the top of each chart in your SpeedCurve dashboards. You can now choose between Aggregate, Minimum, Maximum or Latest. You can hover over any metric to get a tooltip with more context.

See other recent product updates.

Delivering a fast UX on mobile is HARD

The latest Industry Benchmarks snapshot for US ecommerce sites has Etsy in the lead with a Largest Contentful Paint (LCP) time of 4.57 seconds.

Looking at the slowest US ecommerce sites, some of the main pain points are page bloat and unoptimized resources. For example:

  • 100+ requests before important content renders
  • Dozens of blocking scripts
  • Egregious JSON placeholders

Get Started with Core Web Vitals

Speaking of Largest Contentful Paint, want to learn how to make it – and your other Web Vitals – faster? We created this guide to understanding what makes each Vital slower and, more important, how to fix them.

Interaction to Next Paint: A new measure of responsiveness

Before we leave the topic of Core Web Vitals, Google engineer Annie Sullivan (@anniesullie) recently gave a talk at Web Directions' Lazy Load conference on the new Interaction to Next Paint (INP) metric. INP measures a page's responsiveness to user input. Early analysis suggests that it's a more meaningful metric than First Input Delay (which is the current Web Vital for responsiveness). You can see Annie's slides here.

Airbnb's trip to Linaria

I love seeing how behind-the-scenes changes can improve performance metrics. Joe Lencioni (@lencioni) at Airbnb shares how they migrated to a new styling framework and saw improvements to First Contentful Paint and Total Blocking Time.

What GOV.UK learned from one year of real user monitoring (RUM) data

"One of the most important things we’ve learned is that GOV.UK is already a really quick website." This is a great case study from Matt Hobbs (@TheRealNooshu) at GOV.UK, which has a stated goal to deliver a fast experience to 100% of its users.

What should your RUM sample rate be?

Being able to set a sample rate in your real user monitoring (RUM) tool allows you to monitor your pages while managing your spending. It's a great option if staying within a budget is important to you. But refining your sample rate can be hit or miss if you aren’t careful. Cliff Crocker (@cliffcrocker) did some research to help guide you on finding the best sample rate for your RUM data.

NEW! Compare third parties across your pages

With dozens – and sometimes even hundreds – of third-party scripts on a page, it can be hard to figure out which ones are slowing down your site. When comparing two synthetic tests, you now have the ability to compare common third parties, as well as identify which third parties are unique to each test. Using this feature, you can quickly identify new and problematic third parties. (This short video explains how to diagnose third-party regressions in SpeedCurve.)

The developer experience on the Optimization Team

The Optimization Team is a new team at Insider that has quickly proven to have an important role at the company. Its responsibilities include site performance improvements, monitoring, display ad performance, and SEO. First and foremost, the team members are performance evangelists.

Bryan Fellerath shares how the team spent the first quarter of the year focusing on documenting tools and methods for performance monitoring and improvements. As he reports, "This resulted in some unexpected improvements to our team’s knowledge of our tools and methods."

Mark your calendar!

We're very excited to be supporters of some of our favourite in-person events returning this year!

Photo of SmashingConf audience throwing balloons in the air

I'm planning to get to at least a couple of these events – and I'm doing a talk at Hopefully I'll see you there!