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Riccardo Margiotta @riccardomargiotta.co.uk · 31/10/2025

Another year of #PerfNow is done! My poor wee brain is full, but I've got so many practical takeaways to research and try. I've caught up with familiar faces, spoken to the very approachable 'big names' in the #webperf community, and met so many people for the first time. Can't wait to do it again.

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Riccardo Margiotta @riccardomargiotta.co.uk · 31/10/2025

#PerfNow: BOO! (A little jump-scare as you scroll. Happy Halloween!)

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Riccardo Margiotta @riccardomargiotta.co.uk · 31/10/2025

Super talk from @tunetheweb.com on Speculation Rules. Been nervous about using them for fear of false positives on things like Google Analytics. The upcoming prerender_until_script logic sounds like exactly what I need - you'll benefit from fetching subresources, but won't execute scripts. #PerfNow

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Riccardo Margiotta @riccardomargiotta.co.uk · 31/10/2025

A wise man once said... "Simple to use, progressive enhancement, built in APIs are the best!" - @tunetheweb.com Yep, he's onto something. loading=lazy and fetchpriority=high are wonderfully simple 'cheat codes', and some of my favourite additions to the world of #webperf. #PerfNow

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Riccardo Margiotta @riccardomargiotta.co.uk · 31/10/2025

@mmocny.com talking about some super cool new measurements coming to Chrome - such as the equivalent of LCP but for 'soft' navigations like those in SPAs. That has the potential to start measuring a huge blind spot affecting a very significant portion of the web. #PerfNow #webperf

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Riccardo Margiotta @riccardomargiotta.co.uk · 31/10/2025

Be aware of "survivor bias" in your metrics. Users having a fast experience will view more pages and have longer sessions. Your RUM data is always inherently biased towards those with fast experiences. @andydavies.me #PerfNow #webperf

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Riccardo Margiotta @riccardomargiotta.co.uk · 31/10/2025

Cross-browser testing is an act of user advocacy. As much as Chrome has pushed the web forward, if that's all we test we could be missing big gotchas. Meet users wherever they are, no matter the scenario. @timkadlec.bsky.social is crushing it, as the kids are saying these days. #PerfNow #webperf

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Riccardo Margiotta @riccardomargiotta.co.uk · 30/10/2025

Be the interpreter for your non-technical stakeholders. Milliseconds don't mean much to most people, make the data relatable. "Now they get a smoother experience that's over 50% faster." @ethangardner.com on making performance allies. #PerfNow #webperf

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Riccardo Margiotta @riccardomargiotta.co.uk · 30/10/2025

So many of the optimisations we make for web performance make for a more sustainable web. So by improving your LCP or removing that unused legacy JavaScript, you're helping to save the planet. 🙂 @inesakrap.bsky.social #PerfNow #webperf

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Riccardo Margiotta @riccardomargiotta.co.uk · 30/10/2025

Hey @bell.bz, I can confirm this is indeed a great conversation starter (the shirt, not the stroopwaffle)! #PerfNow

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Riccardo Margiotta @riccardomargiotta.co.uk · 30/10/2025

An incredible live demo (very brave) from @michael-hladky.bsky.social showing the performance impact of the contain and content-visibility CSS properties on layout calculation and paint. These have been on my TODO list for a long time, I'm feeling braver to experiment now! #PerfNow #webperf

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Riccardo Margiotta @riccardomargiotta.co.uk · 30/10/2025

Just like web performance work, accessibility winds up being less expensive the earlier you implement it. Build accessibility in from the start, rather than bolting it on - make it part of the process. @marcysutton.com #webperf #PerfNow #a11y

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Riccardo Margiotta @riccardomargiotta.co.uk · 30/10/2025

From a paper in the 1980s and still relevant today: "What if we measured performance by the number of keyboard commands it took to complete a task?" I've spent plenty of time tabbing around my individual pages, but need to start considering full user journeys. @marcysutton.com #webperf #PerfNow

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Riccardo Margiotta @riccardomargiotta.co.uk · 30/10/2025

In #webperf, we over-focus on worst case scenarios, particularly cold starts. Don't test unlikely scenarios like a checkout page with no basket items, or as a landing page. Pasting URLs into perf tools isn't the same as a real user clicking around. @csswizardry.com #PerfNow

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Riccardo Margiotta @riccardomargiotta.co.uk · 30/10/2025

Be aware of synthetic tests using slow defaults. If you're fortunate enough to have users with decently powerful devices and decent connections, overly pessimistic lab results are useless. Pick settings matching at most your P75 - align lab data with real users. @csswizardry.com #webperf #PerfNow

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Riccardo Margiotta @riccardomargiotta.co.uk · 30/10/2025

The #webperf industry has settled on P75 as our benchmark. P75 isn't very ambitious. "It's fine for 25% of our customers to have a bad experience, we don't mind." Why not aim for p95? @csswizardry.com #PerfNow

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Riccardo Margiotta @riccardomargiotta.co.uk · 30/10/2025

Google's performance thresholds are not your thresholds. Remember that Core Web Vitals are certainly a good starting point, but not the end goal. Don't aim for somebody else's target, correlate with your own real user conversions and set your own goals. @tammyeverts.com #PerfNow #webperf

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Riccardo Margiotta @riccardomargiotta.co.uk · 30/10/2025

Our opening #PerfNow keynote is from @tammyeverts.com, as always giving out the best vibes in all of #webperf (and also Halloween candy). "Fast is magical." But how fast is fast enough? If you're not getting any return on your efforts, are you done? Pragmatic vs magic. #Pragmagical

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Riccardo Margiotta @riccardomargiotta.co.uk · 30/10/2025

Test, test, one, two... Got my coffee, got my croissant, and I'm ready to hear about all things #webperf! #PerfNow

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Riccardo Margiotta @riccardomargiotta.co.uk · 29/10/2025

@screenspan.net talks about approaches for making your alerts meaningful, reducing noise and false positives. And @programmingart.bsky.social really commits to the presentation theme. #PerfNow #webperf

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Riccardo Margiotta @riccardomargiotta.co.uk · 29/10/2025

"But Andrea, the synchronous tracking code is secretly hidden deep within Google Tag Manager!" @verlok.bsky.social is calling me out, and I'm not sure I like it. 😅 But some great tips on common INP mistakes. #PerfNow #webperf

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Riccardo Margiotta @riccardomargiotta.co.uk · 29/10/2025

A terrific lineup at the #PerfNow pre-event, performance.sync(). I'm making a mental note to generate all my graphs using emoji from now on. #webperf

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Riccardo Margiotta @riccardomargiotta.co.uk · 29/10/2025

In what seems to have become a ritual, I always stop at Black Gold Coffee on the way to my hotel after landing in Amsterdam for #PerfNow. This hipster coffee shop/record store is pushing it a bit even for my beardy face!

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Riccardo Margiotta @riccardomargiotta.co.uk · 28/10/2025

The detailed page breakdowns and filtering, on so many sessions, mean that I've found performance issues way deeper into customer journeys than I've seen before in CrUX. The team's done a fantastic job on this, looks to be in great shape for launch. Lots to explore when I get back from the conf.

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Riccardo Margiotta @riccardomargiotta.co.uk · 28/10/2025

I'm getting psyched up for #PerfNow, so what better time to receive an early access invite for Calibreapp's new Real User Monitoring (RUM)? Gave it a bit of a load test over the weekend. 😅 It didn't miss a beat, so now I'm having fun doing a #WebPerf deep dive...

Calibre web performance dashboard showing Core Web Vital metrics for 559,000 Real User Monitoring sessions.

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Riccardo Margiotta @riccardomargiotta.co.uk · 15/11/2024

It's a wrap! We made it! Take a minute to recover, let all those awesome new learnings percolate in your brain, and leave your notes and to-do lists for Monday. 🙂 #PerfNow

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Riccardo Margiotta @riccardomargiotta.co.uk · 15/11/2024

"Experimenting includes knowing whether the experiment worked." @anniesullie.bsky.social #PerfNow

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Riccardo Margiotta @riccardomargiotta.co.uk · 15/11/2024

Don't forget to celebrate success! 29,420 years of time saved across CWV in 2024! 🎉 @anniesullie.bsky.social #PerfNow

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Riccardo Margiotta @riccardomargiotta.co.uk · 15/11/2024

A very clear way to demonstrate the performance inequality gap. There's a direct correlation between Interaction to Next Paint (INP) scores and the amount of RAM on a user's device. @karlijnlowik.bsky.social @erwinhofman.bsky.social #PerfNow

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Riccardo Margiotta @riccardomargiotta.co.uk · 15/11/2024

I've recently been trying to optimise the layout shift that occurs when the fallback font swaps out for our branded web font. Super helpful to have this detailed walkthrough from @mandymichael.bsky.social! #PerfNow

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Riccardo Margiotta @riccardomargiotta.co.uk · 15/11/2024

Day 2 of #PerfNow kicks off with @tkadlec.bsky.social telling us he's optimistic. "We have more options than ever in this community. I think we have more tools than ever. We're not going to solve performance by writing more bytes. Betting on the browser is our best chance at long-term success."

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Riccardo Margiotta @riccardomargiotta.co.uk · 15/11/2024

Thank the performance gods (and @debugbear.com!) for the wonderful barista! #PerfNow

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Riccardo Margiotta @riccardomargiotta.co.uk · 14/11/2024

A powerful talk from @slightlyoff.bsky.social at #PerfNow. 75% of new devices with browsers are phones. The web is not successful on mobile. Many things try to steal links from the web and move them to apps from closed, proprietary app stores. The web is losing.

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Riccardo Margiotta @riccardomargiotta.co.uk · 14/11/2024

It's simple, but easy to forget - "Your conditions are not the conditions of your user. Have empathy." But we all have moments where our conditions aren't ideal, so we all benefit from #webperf improvements. @szynszyliszys.bsky.social #PerfNow

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Riccardo Margiotta @riccardomargiotta.co.uk · 14/11/2024

Most web performance metrics and resources are developed with a privileged user in mind. At most, we suffer 'accidental' performance issues, like browsing on a train. For some, good web performance is not achievable at all. @szynszyliszys.bsky.social #PerfNow

It's a problem for anyone:
Using an old device.
Located in a rural area.
Using an Enterprise app that's hard to optimise.

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Riccardo Margiotta @riccardomargiotta.co.uk · 14/11/2024

Me: *immediately messages a colleague* Yep. Guess I'll be tweaking our NGINX config next week. 😅 Thanks @paulcalvano.bsky.social! Love it when things get super practical at #PerfNow.

NGINX's default gzip compression level is 1.

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Riccardo Margiotta @riccardomargiotta.co.uk · 14/11/2024

An example of a site with 379 unused preloads. I'm on the verge of tears. 😭 #PerfNow

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Riccardo Margiotta @riccardomargiotta.co.uk · 14/11/2024

No one goes to work to do a bad job. Clichéd perhaps, but it's important to treat mistakes without a blame culture. Create a learning opportunity. But that said, @paulcalvano.bsky.social is walking us through 17 #webperf mistakes that stem from best intentions but lead to worse results. #PerfNow

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Riccardo Margiotta @riccardomargiotta.co.uk · 14/11/2024

Web performance and accessibility go hand in hand. To make a radio button in Material UI, you need 6 HTML elements, 66 CSS selectors, and 30KB minified JavaScript. Don't throw out what the browser gives us for free. #PerfNow #webperf @ericwbailey.website

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Riccardo Margiotta @riccardomargiotta.co.uk · 14/11/2024

It's all for nothing if you don't have a plan for #webperf regressions. "Shall we pretend we haven't seen that?" isn't a plan! Having agreed rules based on the severity and duration of regressions to your KPIs means you don't need to ask permission to rollback. #PerfNow @csswizardry.com

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Riccardo Margiotta @riccardomargiotta.co.uk · 14/11/2024

Different members of teams and businesses need different levels of 'disclosure' on performance metrics. Your CEO probably doesn't need to know about TTFB! @csswizardry.com #PerfNow

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Riccardo Margiotta @riccardomargiotta.co.uk · 14/11/2024

A rather... sobering... start to the morning from @tammyeverts.bsky.social discussing the #webperf landscape. #PerfNow

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Riccardo Margiotta @riccardomargiotta.co.uk · 13/11/2024

"Collecting UX-impacting metrics everyone understands means we can improve them together." Ideas from bsky.app/profile/kurt... for moving beyond Core Web Vitals to custom metrics relevant to your product that everyone can understand and get behind. #PerfNow #webperf

When does my H1 render? When does my primary feature show up or become interactive?

Invisible metrics at Framer: hydration duration, cookie banner start time

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Riccardo Margiotta @riccardomargiotta.co.uk · 13/11/2024

My favourite thing about Amsterdam is wandering around, being on one side of a canal, and wondering how to get to the *other* side of the canal. Also, playing Frogger with bikes.

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