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Core Web Vitals tips, fighting UX regression & inspiring case studies from REI and Shopify

Feb 1, 2023


Hi there,

I don't know about you, but for me the past few weeks have blazed past. Between recovering from the holidays and making plans for 2023, January was a full month!

In this edition, we've corralled some great stuff for you, including:

  • The latest Industry Benchmarks for retail and media
  • Inspiring case studies from REI, Shopify, and Adevinta
  • Tons of optimization tips, especially for Core Web Vitals
  • New best practices for staying fast and fighting regression with performance budgets
  • Where you'll find SpeedCurve in 2023

I'm so excited for the year ahead, and looking forward to sharing lots more with you next month. Until then, stay well. :)

m: @tammy
t: @tameverts


Industry Page Speed Benchmarks

It was so great to look at the latest Retail Page Speed Benchmarks and see that 13 out of the 14 retail sites we track are all within Google's recommended Largest Contentful Paint thresholds – with desktop LCP times of 2.5s or less!

On the other hand, I also looked at the Media Page Speed Benchmarks for mobile and saw that LCP times range from 6s to 64s. (I read most of my news on a five-year-old iPhone over spotty networks, so this was disheartening, but not surprising.)

Our Industry Page Speed Benchmarks – which also cover tech, travel, finance, and auto industries in the US, EU/UK, and Japan – are public-facing (so no login required) and updated daily. You can also dig deeper and see test details and waterfall charts for each site.

If you want to track your own pages alongside your competitors, you can do that within your SpeedCurve account. Learn how to set up your own competitive benchmarking dashboard.

Catching the wheel at REI

Casey Carroll • REI

"Days before the holiday sales change freeze, the web performance and analytics teams deployed a change that drastically improved front-end performance. A new configuration on a third-party script led to a 60% improvement to First Contentful Paint (FCP). This rocketed us to the top of our industry performance leader board. Most importantly, our real user data met Google’s Core Web Vitals goals: A strong indication of a great customer experience."

Optimizing images for performance on Shopify

Sia Karamalegos • Shopify

As Sia writes, "Images are key to user experience, especially in ecommerce. It is difficult to sell a product unless a customer can see it." In this post, she focuses on how images can affect page speed and layout shift, specifically looking at Largest Contentful Paint (LCP) and Cumulative Layout Shift (CLS) in the real world at Shopify.

Six months with Adevinta

Alex Mir • Adevinta

Seeing your company through the eyes of a new team member is such a valuable exercise. Alex shares his personal experiences of joining Adevinta as a Junior Frontend Engineer. It's great to see how Adevinta invites this feedback on their tech blog. (Pretty nice to see the SpeedCurve shout-out on the list of tools, too!)

The Performance Inequality Gap, 2023

Alex Russell

I couldn't agree more with Alex's statement: "When digital is society's default, slow is exclusionary." In the final instalment of his six-part series "The Performance Inequality Gap", Alex opens our eyes to device, network, and CPU realities that are hurting performance outside our privileged tech world.

And the inequality gap is continuing to worsen. Among other things, Alex points out:

"Meanwhile, sites continue to send more script than is reasonable for 80+% of the world's users, widening the gap between the haves and the have-nots. This is an ethical crisis for frontend."

Top Core Web Vitals recommendations for 2023

Chrome DevRel team • Google

Okay, so now that we know how things are getting worse, what can we do to make them better? Luckily, the Chrome DevRel team has put together a collection of best practices that they believe are the most effective ways to improve your Core Web Vitals performance in 2023.

Optimizing Largest Contentful Paint (LCP)

Harry Roberts • CSS Wizardry

Oh my gosh, I can't say enough good things about this talk from Harry at PerfNow in November. So many takeaways! If you care about web performance and UX, then you should care about optimizing your hero images. Tracking and fixing your Largest Contentful Paint (LCP) time is a good place to start. Watch the full talk here.

Optimizing Time to First Byte (TTFB)

Jeremy Wagner • Google

Sometimes, in our rush to embrace shiny new metrics, we risk neglecting older metrics that are as crucial now as they've ever been. In this article, Jeremy revisits Time to First Byte, which precedes every other meaningful UX metric – meaning that a slow TTFB hurts all your other metrics.

As a rough guide, you should aim to have a TTFB less than 0.8s for the 75th percentile of your users. Jeremy covers how to get there.

Real-world performance budgets

Tammy Everts • SpeedCurve

After you've done all the heavy lifting of optimizing for your most important metrics, the next goal is to STAY fast, right? In November I did a talk about real-world performance budgets at PerfNow. (TL;DR if you're not using budgets to fight performance/UX regressions and keep your site fast for your users, you should be!) The full video is now available to watch here.

ICYMI: 2022 SpeedCurve recap

Here's a recap of what we got up to in 2022, including:

  • Awesome new RUM & synthetic dashboards
  • Core Web Vitals badges on your Lighthouse audits
  • Expanded Industry Benchmarks

We added a lot of new functionality, which we're really excited about. If you have any questions about any of it, please don't hesitate to give us a shout.

SmashingConf and PerfNow... tally-ho!

We're so excited to once again be sponsors for SmashingConf and in 2023. We'd love to see you there!

Questions? Feedback? Let me know!

As always, I welcome your questions and feedback. Let me know your thoughts by replying to this email or sending a note to