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🤝 RUM & Synthetic, Together Forever

I’ve talked for a long time about why I feel it’s important for companies to have both RUM and synthetic monitoring (you probably need Chrome User Experience data too, which is not RUM—that’s a soapbox I’m willing to die on but more on that in the future), but that’s never been more important than today.

Metrics like Interaction to Next Paint are virtually impossible to efficiently identify and fix with synthetic tooling (a few have tried, but my experience so far has been that the attempts are pretty flaky at best). Synthetic tooling can help with Cumulative Layout Shift, but because there are so many ways that shifting can happen after page load, scripting them all can be incredible challenging.

But even as we make RUM more diagnostic with better, more actionable information about what is prompting our metrics to be slow, it still can’t get anywhere near the level of depth we can get from synthetic tooling.

I’m finding myself feeling more and more constrained when I try to help organizations that only have one type of data the other in place. We can get the job done but it is a lot faster if both types of data are present and we can dip seamlessly between the two, using them both to help interpret the other.

I’m not sure there’s a better investment for performance-minded organizations in 2024 than to make sure they have robust RUM and synthetic monitoring in place.

🏎️ Walmart’s Race to Green INP

Speaking of INP, it looks like Walmart has been putting in some serious work on getting their INP improved. I dig the animation Pim put together showing their progress over the past 8 months.


A couple things I like about this:

It sounds like we’ll hopefully be hearing more soon about how exactly Walmart improved INP, and I’ll definitely be watching out for that.

🌊 A series of tubes, under the sea

Well this was one of my favorite reads in awhile for sure.

The Verge has a great article talking about the 800,000 miles or so of cables running under the ocean to keep the internet running. Apparently around 200 times or so each year a cable breaks somewhere in the ocean (honestly, doesn’t it feel like you would expect it to happen more often?) but a network of ships are on standby to go out and fix them before things get out of hand.

It’s an incredible story, diving (heh, ocean pun) into the life of the people on these ships and how exactly they go about repairing cable breaks as deep as 20,000 feet under the sea.

Definitely one of those “how on earth does the internet ever work” kind of reads.

📆 Performance Events

Courtesy of Stoyan, there is now a Web Performance Events directory on PerfPlanet. It’s pretty straightforward to add your own events too.

It’s an awesome resource and there are already some great events listed. I’m hoping to see this fill out more. Events have been really slow to come back and I miss them—there’s something special about hanging out in person with like-minded folks and learning from each other. Here’s hoping we see more events—from local meetups to full-on conferences—start to pop up again.