@erwinhofman.bsky.social
Google Developer Expert in web performance
CTO @ RUMvision.com
Also sharing over at https://linkedin.com/in/erwinhofman
CTO @ RUMvision.com
Also sharing over at https://linkedin.com/in/erwinhofman
#LCP and #INP support in #Safari really coming close now (maybe even in 2025?) as Safari 26.2 Beta Release Notes includes:
- support for the Event Timing API
- Largest Contentful Paint metric
Great work by the #Webkit team!
A blogpost:
www.rumvision.com/blog/safari-...
- support for the Event Timing API
- Largest Contentful Paint metric
Great work by the #Webkit team!
A blogpost:
www.rumvision.com/blog/safari-...
Safari catching up: INP and LCP support in the same beta release
Real User Monitoring
www.rumvision.com
November 5, 2025 at 10:35 AM
#LCP and #INP support in #Safari really coming close now (maybe even in 2025?) as Safari 26.2 Beta Release Notes includes:
- support for the Event Timing API
- Largest Contentful Paint metric
Great work by the #Webkit team!
A blogpost:
www.rumvision.com/blog/safari-...
- support for the Event Timing API
- Largest Contentful Paint metric
Great work by the #Webkit team!
A blogpost:
www.rumvision.com/blog/safari-...
#perfnow early morning performance session with @stuart-mcmillan.com (although he did a longer version 😅)
Now on to the real event @ @perfnow.nl! 😍
Now on to the real event @ @perfnow.nl! 😍
October 30, 2025 at 8:42 AM
#perfnow early morning performance session with @stuart-mcmillan.com (although he did a longer version 😅)
Now on to the real event @ @perfnow.nl! 😍
Now on to the real event @ @perfnow.nl! 😍
@perfnow.nl Amsterdam weather update for those that haven't packed yet:
Not too bad during the perf days as it will become slightly warmer + less rainy from Wednesday to Friday.
Not too bad during the perf days as it will become slightly warmer + less rainy from Wednesday to Friday.
October 25, 2025 at 5:07 PM
@perfnow.nl Amsterdam weather update for those that haven't packed yet:
Not too bad during the perf days as it will become slightly warmer + less rainy from Wednesday to Friday.
Not too bad during the perf days as it will become slightly warmer + less rainy from Wednesday to Friday.
@andydavies.me need a LoAF image for your @perfnow.nl talk?
I just ran into this at Schiphol 🤓😆
#LoAF #INP
I just ran into this at Schiphol 🤓😆
#LoAF #INP
October 16, 2025 at 8:31 AM
@andydavies.me need a LoAF image for your @perfnow.nl talk?
I just ran into this at Schiphol 🤓😆
#LoAF #INP
I just ran into this at Schiphol 🤓😆
#LoAF #INP
Nerdy stuff! @mozilla.org #Firefox just enabled support for #INP with v144 🎉
I dived into our raw RUMvision data. And yep, can confirm that it works when using Google's web-vitals #JavaScript library 😍
(updated) article + chart + baseline badges in a blogpost:
www.rumvision.com/blog/firefox...
I dived into our raw RUMvision data. And yep, can confirm that it works when using Google's web-vitals #JavaScript library 😍
(updated) article + chart + baseline badges in a blogpost:
www.rumvision.com/blog/firefox...
October 15, 2025 at 8:19 AM
Nerdy stuff! @mozilla.org #Firefox just enabled support for #INP with v144 🎉
I dived into our raw RUMvision data. And yep, can confirm that it works when using Google's web-vitals #JavaScript library 😍
(updated) article + chart + baseline badges in a blogpost:
www.rumvision.com/blog/firefox...
I dived into our raw RUMvision data. And yep, can confirm that it works when using Google's web-vitals #JavaScript library 😍
(updated) article + chart + baseline badges in a blogpost:
www.rumvision.com/blog/firefox...
Weekend! But also: looking back at quite the event, venue and community! I’ve only spoken to a purely #SEO audience a handful of times, but this one was truly energizing!
A stable internet was needed to pull off the live quiz.
Some attendees couldn’t even join in 😬
1/4
A stable internet was needed to pull off the live quiz.
Some attendees couldn’t even join in 😬
1/4
October 11, 2025 at 9:48 AM
Weekend! But also: looking back at quite the event, venue and community! I’ve only spoken to a purely #SEO audience a handful of times, but this one was truly energizing!
A stable internet was needed to pull off the live quiz.
Some attendees couldn’t even join in 😬
1/4
A stable internet was needed to pull off the live quiz.
Some attendees couldn’t even join in 😬
1/4
Aftermath sketch of our talk 🤩
Someone in the audience of which I thought was taking notes the old school way, appeared to have been making sketches 🤓
Huge thank you to Jeroen Heijmans for doing + sharing this!
1/2
Someone in the audience of which I thought was taking notes the old school way, appeared to have been making sketches 🤓
Huge thank you to Jeroen Heijmans for doing + sharing this!
1/2
First #Fronteers presentation was by @karlijnlowik.bsky.social and @erwinhofman.bsky.social, about web performance and RUM!
October 4, 2025 at 7:38 AM
Aftermath sketch of our talk 🤩
Someone in the audience of which I thought was taking notes the old school way, appeared to have been making sketches 🤓
Huge thank you to Jeroen Heijmans for doing + sharing this!
1/2
Someone in the audience of which I thought was taking notes the old school way, appeared to have been making sketches 🤓
Huge thank you to Jeroen Heijmans for doing + sharing this!
1/2
New speaking gig confirmed: #SEOBenelux 🤟
Happening next week in between my 2 other scheduled talks this month!
But this edition and talk will be different:
→ pure #SEO audience
→ bringing me back at another SEO event
→ this time in #Antwerp, October 10th
1/2
Happening next week in between my 2 other scheduled talks this month!
But this edition and talk will be different:
→ pure #SEO audience
→ bringing me back at another SEO event
→ this time in #Antwerp, October 10th
1/2
October 2, 2025 at 11:54 AM
New speaking gig confirmed: #SEOBenelux 🤟
Happening next week in between my 2 other scheduled talks this month!
But this edition and talk will be different:
→ pure #SEO audience
→ bringing me back at another SEO event
→ this time in #Antwerp, October 10th
1/2
Happening next week in between my 2 other scheduled talks this month!
But this edition and talk will be different:
→ pure #SEO audience
→ bringing me back at another SEO event
→ this time in #Antwerp, October 10th
1/2
Many people don't know this: you can help shape the web with just an upvote (But: Today is the last day!)
When I started frontend dev 20+ years ago, browsers felt untouchable to me: everything is set in stone and decided already.
But over time (and especially since 2021) I learned that:
1/4
When I started frontend dev 20+ years ago, browsers felt untouchable to me: everything is set in stone and decided already.
But over time (and especially since 2021) I learned that:
1/4
Interop 2026: Key APIs for sitespeed & RUM
Real User Monitoring
www.rumvision.com
September 24, 2025 at 2:38 PM
Many people don't know this: you can help shape the web with just an upvote (But: Today is the last day!)
When I started frontend dev 20+ years ago, browsers felt untouchable to me: everything is set in stone and decided already.
But over time (and especially since 2021) I learned that:
1/4
When I started frontend dev 20+ years ago, browsers felt untouchable to me: everything is set in stone and decided already.
But over time (and especially since 2021) I learned that:
1/4
@fronteers.bsky.social speaking gig is coming up soon (Oct 3rd), but first:
Visiting #MeetMagento Italy!
📍 happening in Rome
📅 Thursday September 25th
☕ Coffee break sponsored by RUMvision.com
Travelling with @karlijnlowik.bsky.social as she will be talking about #sitespeed, #RUM, #memes + more
Visiting #MeetMagento Italy!
📍 happening in Rome
📅 Thursday September 25th
☕ Coffee break sponsored by RUMvision.com
Travelling with @karlijnlowik.bsky.social as she will be talking about #sitespeed, #RUM, #memes + more
September 18, 2025 at 7:09 PM
@fronteers.bsky.social speaking gig is coming up soon (Oct 3rd), but first:
Visiting #MeetMagento Italy!
📍 happening in Rome
📅 Thursday September 25th
☕ Coffee break sponsored by RUMvision.com
Travelling with @karlijnlowik.bsky.social as she will be talking about #sitespeed, #RUM, #memes + more
Visiting #MeetMagento Italy!
📍 happening in Rome
📅 Thursday September 25th
☕ Coffee break sponsored by RUMvision.com
Travelling with @karlijnlowik.bsky.social as she will be talking about #sitespeed, #RUM, #memes + more
According to @httparchive.org 2024 research, 16% of mobile pages are still lazyloading their #LCP image!
This could cost you a relation with customer!
Fun fact: this percentage is kinda different from mobile data from sites using RUMvision.com (23%, see screenshot in 5th tweet)
1/6
This could cost you a relation with customer!
Fun fact: this percentage is kinda different from mobile data from sites using RUMvision.com (23%, see screenshot in 5th tweet)
1/6
August 11, 2025 at 3:30 PM
According to @httparchive.org 2024 research, 16% of mobile pages are still lazyloading their #LCP image!
This could cost you a relation with customer!
Fun fact: this percentage is kinda different from mobile data from sites using RUMvision.com (23%, see screenshot in 5th tweet)
1/6
This could cost you a relation with customer!
Fun fact: this percentage is kinda different from mobile data from sites using RUMvision.com (23%, see screenshot in 5th tweet)
1/6
We just added something nerdy to our tool, as treemaps seems to be hot in #JavaScript + web #performance world 🔥
When using RUMvision - Core Web Vitals monitoring to track #UX in real-time, we already show site owners a third party dashboard.
But we now added a treemap-view as well:
1/4
When using RUMvision - Core Web Vitals monitoring to track #UX in real-time, we already show site owners a third party dashboard.
But we now added a treemap-view as well:
1/4
July 18, 2025 at 12:16 PM
We just added something nerdy to our tool, as treemaps seems to be hot in #JavaScript + web #performance world 🔥
When using RUMvision - Core Web Vitals monitoring to track #UX in real-time, we already show site owners a third party dashboard.
But we now added a treemap-view as well:
1/4
When using RUMvision - Core Web Vitals monitoring to track #UX in real-time, we already show site owners a third party dashboard.
But we now added a treemap-view as well:
1/4
My scariest talk ever? Probably this one, where we talked about a topic (#INP) at a sold out event with 10+ Googlers. And 9 of them being the authors of our subject. Imagine that!
It's like explaining how to invest while Warren Buffett is sitting in the audience.. x9 😬
1/4
It's like explaining how to invest while Warren Buffett is sitting in the audience.. x9 😬
1/4
July 9, 2025 at 8:53 AM
My scariest talk ever? Probably this one, where we talked about a topic (#INP) at a sold out event with 10+ Googlers. And 9 of them being the authors of our subject. Imagine that!
It's like explaining how to invest while Warren Buffett is sitting in the audience.. x9 😬
1/4
It's like explaining how to invest while Warren Buffett is sitting in the audience.. x9 😬
1/4
Paul Kinlan and @rachelandrew.bsky.social in their opening remarks, and (Paul) then covering "new in Chrome" at #GoogleIOConnect including #CoreWebVitals and #Baseline
June 25, 2025 at 12:04 PM
Paul Kinlan and @rachelandrew.bsky.social in their opening remarks, and (Paul) then covering "new in Chrome" at #GoogleIOConnect including #CoreWebVitals and #Baseline
We overlaid collected #CoreWebVitals from our users (and their visitors) from #Spain + #Portugal with electricity usage chart from Red Eléctrica.
We saw a strong correlation:
[A] On April 27th and 29th, traffic dips after noon as a result of lunch time and possibly siesta
1/2
We saw a strong correlation:
[A] On April 27th and 29th, traffic dips after noon as a result of lunch time and possibly siesta
1/2
April 30, 2025 at 10:00 AM
We overlaid collected #CoreWebVitals from our users (and their visitors) from #Spain + #Portugal with electricity usage chart from Red Eléctrica.
We saw a strong correlation:
[A] On April 27th and 29th, traffic dips after noon as a result of lunch time and possibly siesta
1/2
We saw a strong correlation:
[A] On April 27th and 29th, traffic dips after noon as a result of lunch time and possibly siesta
1/2
If you're reading this then please don't ever invest in #PageSpeed / #CoreWebVitals!
By not investing, you:
→ get to keep that money in your business 👌
→ will allow my current Core Web Vitals clients to actually do get the additional #SEO boost (as part of Page Experience ranking signal)
1/2
By not investing, you:
→ get to keep that money in your business 👌
→ will allow my current Core Web Vitals clients to actually do get the additional #SEO boost (as part of Page Experience ranking signal)
1/2
April 17, 2025 at 7:17 AM
If you're reading this then please don't ever invest in #PageSpeed / #CoreWebVitals!
By not investing, you:
→ get to keep that money in your business 👌
→ will allow my current Core Web Vitals clients to actually do get the additional #SEO boost (as part of Page Experience ranking signal)
1/2
By not investing, you:
→ get to keep that money in your business 👌
→ will allow my current Core Web Vitals clients to actually do get the additional #SEO boost (as part of Page Experience ranking signal)
1/2
My last chance: doing a proof run with a Google webinar happening in exactly 2 days.
With Tony Conway we'll be talking about:
→ #web #features and Can I Use
→ How the (relatively) new #Baseline project simplifies dev decision making
→ Existing and upcoming tools
1/2
With Tony Conway we'll be talking about:
→ #web #features and Can I Use
→ How the (relatively) new #Baseline project simplifies dev decision making
→ Existing and upcoming tools
1/2
RUMvision and Google | Making Baseline actionable with real user data
Ever delayed implementing a modern web feature because you weren't sure if your users' browsers would support it? Or kept heavy polyfills around longer than needed? You're not alone. While Baseline gi...
streamyard.com
April 8, 2025 at 1:21 PM
Many of you might be like me: wanting to use new web features to improve hashtag#pagespeed, but without adding too much hashtag#JavaScript or (future legacy) polyfills 🤓
During audits, I've seen:
1️⃣ polyfills for responsive images (yes I know, very outdated)
1/5
During audits, I've seen:
1️⃣ polyfills for responsive images (yes I know, very outdated)
1/5
April 3, 2025 at 1:45 PM
Many of you might be like me: wanting to use new web features to improve hashtag#pagespeed, but without adding too much hashtag#JavaScript or (future legacy) polyfills 🤓
During audits, I've seen:
1️⃣ polyfills for responsive images (yes I know, very outdated)
1/5
During audits, I've seen:
1️⃣ polyfills for responsive images (yes I know, very outdated)
1/5
Yesterday I was welcomed by Dutch Digital Agency Webreact @ their awesome office! 😀
With a group of 12, we went through all things #pagespeed:
1️⃣ #CoreWebVitals metrics
2️⃣ #Lighthouse vs #CrUX vs #RUM
3️⃣ WebPageTest & Chrome DevTools features
4️⃣ new browser APIs allowing us to use less JS
1/3
With a group of 12, we went through all things #pagespeed:
1️⃣ #CoreWebVitals metrics
2️⃣ #Lighthouse vs #CrUX vs #RUM
3️⃣ WebPageTest & Chrome DevTools features
4️⃣ new browser APIs allowing us to use less JS
1/3
March 19, 2025 at 4:15 PM
Yesterday I was welcomed by Dutch Digital Agency Webreact @ their awesome office! 😀
With a group of 12, we went through all things #pagespeed:
1️⃣ #CoreWebVitals metrics
2️⃣ #Lighthouse vs #CrUX vs #RUM
3️⃣ WebPageTest & Chrome DevTools features
4️⃣ new browser APIs allowing us to use less JS
1/3
With a group of 12, we went through all things #pagespeed:
1️⃣ #CoreWebVitals metrics
2️⃣ #Lighthouse vs #CrUX vs #RUM
3️⃣ WebPageTest & Chrome DevTools features
4️⃣ new browser APIs allowing us to use less JS
1/3
Client: "We don't have any non-JavaScript users"
"No, all your users are non-JS while they're downloading your JS"
I'm actually stealing a tweet from Jake Archibald (ex-Google, now @ Spotify) here:
x.com/jaffathecake...
Fun fact:
📅 Jake tweeted this a decade ago at May 28, 2012
1/4
"No, all your users are non-JS while they're downloading your JS"
I'm actually stealing a tweet from Jake Archibald (ex-Google, now @ Spotify) here:
x.com/jaffathecake...
Fun fact:
📅 Jake tweeted this a decade ago at May 28, 2012
1/4
March 17, 2025 at 3:35 PM
Client: "We don't have any non-JavaScript users"
"No, all your users are non-JS while they're downloading your JS"
I'm actually stealing a tweet from Jake Archibald (ex-Google, now @ Spotify) here:
x.com/jaffathecake...
Fun fact:
📅 Jake tweeted this a decade ago at May 28, 2012
1/4
"No, all your users are non-JS while they're downloading your JS"
I'm actually stealing a tweet from Jake Archibald (ex-Google, now @ Spotify) here:
x.com/jaffathecake...
Fun fact:
📅 Jake tweeted this a decade ago at May 28, 2012
1/4
Reposted
We've updated our timelines for deprecating the unload event.
We're looking to start ramping this up soon, starting with the most visited site—Google (nothing like eating your own dog food!) and then the other top 50 sites, followed by the general web.
developer.chrome.com/docs/web-pla...
We're looking to start ramping this up soon, starting with the most visited site—Google (nothing like eating your own dog food!) and then the other top 50 sites, followed by the general web.
developer.chrome.com/docs/web-pla...
March 12, 2025 at 4:34 PM
We've updated our timelines for deprecating the unload event.
We're looking to start ramping this up soon, starting with the most visited site—Google (nothing like eating your own dog food!) and then the other top 50 sites, followed by the general web.
developer.chrome.com/docs/web-pla...
We're looking to start ramping this up soon, starting with the most visited site—Google (nothing like eating your own dog food!) and then the other top 50 sites, followed by the general web.
developer.chrome.com/docs/web-pla...
Awesome #CrUX update by the people from #Google (and also partially available in our free tool as well) 👏
This was added:
→ LCP image subparts
→ LCP resource types
→ Round Trip Time (RTT) tri-bins
→ RTT p75 and histograms
We added #LCP resource type already as well (see attached).
1/4
This was added:
→ LCP image subparts
→ LCP resource types
→ Round Trip Time (RTT) tri-bins
→ RTT p75 and histograms
We added #LCP resource type already as well (see attached).
1/4
February 11, 2025 at 9:41 PM
First public gig of 2025 has been announced, and it'll be a sunny one!
Together with @karlijnlowik.bsky.social I'll be hosting a workshop focusing on debugging #sitespeed & #CoreWebVitals issues via #WebPageTest, #RUM & #DevTools.
General event info + tickets via:
www.linkedin.com/showcase/hyv...
Together with @karlijnlowik.bsky.social I'll be hosting a workshop focusing on debugging #sitespeed & #CoreWebVitals issues via #WebPageTest, #RUM & #DevTools.
General event info + tickets via:
www.linkedin.com/showcase/hyv...
January 28, 2025 at 9:00 AM
First public gig of 2025 has been announced, and it'll be a sunny one!
Together with @karlijnlowik.bsky.social I'll be hosting a workshop focusing on debugging #sitespeed & #CoreWebVitals issues via #WebPageTest, #RUM & #DevTools.
General event info + tickets via:
www.linkedin.com/showcase/hyv...
Together with @karlijnlowik.bsky.social I'll be hosting a workshop focusing on debugging #sitespeed & #CoreWebVitals issues via #WebPageTest, #RUM & #DevTools.
General event info + tickets via:
www.linkedin.com/showcase/hyv...
Few days ago, I asked people about Can I Use vs MDN. #Baseline was the least popular. Guess what? We adopted it anyway 🙃 So that:
→ when web features are mentioned, you'll now see browser support badges in our RUMvision blogposts and other pages
1/4
→ when web features are mentioned, you'll now see browser support badges in our RUMvision blogposts and other pages
1/4
January 11, 2025 at 12:18 PM
Few days ago, I asked people about Can I Use vs MDN. #Baseline was the least popular. Guess what? We adopted it anyway 🙃 So that:
→ when web features are mentioned, you'll now see browser support badges in our RUMvision blogposts and other pages
1/4
→ when web features are mentioned, you'll now see browser support badges in our RUMvision blogposts and other pages
1/4