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Web Vitals, tracking first & third parties, and RUM sampling tips

May 1, 2020

Hi there,

I hope this letter finds you well. These are strange times, but – as you can probably relate to – we here at SpeedCurve are finding that keeping busy really helps.

To that end, we've been working hard at building new features and improving existing ones. We've also been doing the unglamorous-but-important work of updating our Support Centre and adding new support articles. And we've been enjoying all the great research and case studies being produced by other folks in the #webperf community. You can learn more about all of this below. 

We've got more exciting new stuff in the works. Stay tuned!

Until next time,


New! Monitor Web Vitals for a better UX

Web Vitals is a new Google initiative that focuses on these user-centric performance metrics: 

  • Largest Contentful Paint
  • First Input Delay / Total Blocking Time
  • Cumulative Layout Shift

Here's our blog post and short video that explain how to track Web Vitals in SpeedCurve Synthetic and LUX.

New! Track first and third parties

After much feedback from people who love our third-party tracking, we've added the ability to track first-party request groups – and create performance budgets and alerts for them!

Check out our blog post and short video that explain how to turn on tracking for first- and third-party request groups.

When is it a good idea to sample RUM?

When it comes to gathering user data, is it always necessary to monitor ALL THE THINGS? What if you could monitor less traffic – and incidentally, spend less on your RUM – and still get meaningful data? Here are some use cases for when and why data sampling can be a good idea for RUM.

User Timing Level 3

The Chrome team has quietly introduced a fundamental change to how user timing marks work into Chrome 78. For many years now, our own Steve Souders has championed user timing. Steve has always believed you should be able to set a value for a user timing mark or measure. With User Timing Level 3, now you can! 


Some metrics are, admittedly, a bit less straightforward than others. If you've ever found yourself struggling to remember the nuances of metrics like, for example, First CPU Idle, then your struggles are over! Just click on the 'Help' icon on the top-right corner of the chart and you'll expand a handy mini-glossary of the metrics contained within that chart.

Featured FAQs

From the #webperf community