@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
#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
Curve continues, more browsers being updated after lunch? 😅
October 15, 2025 at 3:04 PM
Curve continues, more browsers being updated after lunch? 😅
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...
And I picked up a few insights from the audience too:
→ what tools they typically use
→ how familiar they are with each individual metric
→ if they know who @divingfor.fun is (my very first quiz question which appeared to be a tricky one 😅)
3/4
→ what tools they typically use
→ how familiar they are with each individual metric
→ if they know who @divingfor.fun is (my very first quiz question which appeared to be a tricky one 😅)
3/4
October 11, 2025 at 9:50 AM
And I picked up a few insights from the audience too:
→ what tools they typically use
→ how familiar they are with each individual metric
→ if they know who @divingfor.fun is (my very first quiz question which appeared to be a tricky one 😅)
3/4
→ what tools they typically use
→ how familiar they are with each individual metric
→ if they know who @divingfor.fun is (my very first quiz question which appeared to be a tricky one 😅)
3/4
Which actually proved my points perfectly:
→ web #performance subject still matters as conditions are never the same
→ field data (e.g. #CoreWebVitals) is different from my testruns back home
→ if 75% managed to participate, I’ll take that as a win (just like Google’s 75th percentile 😜)
2/4
→ web #performance subject still matters as conditions are never the same
→ field data (e.g. #CoreWebVitals) is different from my testruns back home
→ if 75% managed to participate, I’ll take that as a win (just like Google’s 75th percentile 😜)
2/4
October 11, 2025 at 9:49 AM
Which actually proved my points perfectly:
→ web #performance subject still matters as conditions are never the same
→ field data (e.g. #CoreWebVitals) is different from my testruns back home
→ if 75% managed to participate, I’ll take that as a win (just like Google’s 75th percentile 😜)
2/4
→ web #performance subject still matters as conditions are never the same
→ field data (e.g. #CoreWebVitals) is different from my testruns back home
→ if 75% managed to participate, I’ll take that as a win (just like Google’s 75th percentile 😜)
2/4
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
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
@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
Pro-tip:
Instead of manually checking this for all your URLs, use a tool like RUMvision.com to scope and track the impact when fixed.
Attached:
We can see that 18% of visited pages lazyloads their LCP via loading=lazy
Slice+dice to template type to see which ones are still lazyloading 💡
5/6
Instead of manually checking this for all your URLs, use a tool like RUMvision.com to scope and track the impact when fixed.
Attached:
We can see that 18% of visited pages lazyloads their LCP via loading=lazy
Slice+dice to template type to see which ones are still lazyloading 💡
5/6
August 11, 2025 at 3:31 PM
Pro-tip:
Instead of manually checking this for all your URLs, use a tool like RUMvision.com to scope and track the impact when fixed.
Attached:
We can see that 18% of visited pages lazyloads their LCP via loading=lazy
Slice+dice to template type to see which ones are still lazyloading 💡
5/6
Instead of manually checking this for all your URLs, use a tool like RUMvision.com to scope and track the impact when fixed.
Attached:
We can see that 18% of visited pages lazyloads their LCP via loading=lazy
Slice+dice to template type to see which ones are still lazyloading 💡
5/6
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
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
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
I could have spent time playing some PS during my Christmas break. But I decided to play with CSS #viewTransitions instead.
Not just the basic #CSS, but applying a bit of tailored #JavaScript thanks to @bram.us his demos.
Here are the results:
1/4
Not just the basic #CSS, but applying a bit of tailored #JavaScript thanks to @bram.us his demos.
Here are the results:
1/4
December 28, 2024 at 3:37 PM
I could have spent time playing some PS during my Christmas break. But I decided to play with CSS #viewTransitions instead.
Not just the basic #CSS, but applying a bit of tailored #JavaScript thanks to @bram.us his demos.
Here are the results:
1/4
Not just the basic #CSS, but applying a bit of tailored #JavaScript thanks to @bram.us his demos.
Here are the results:
1/4