Paul Calvano
@paulcalvano.bsky.social
I’ll be giving a talk about Fonts and Web Perfomance at the Tech SEO Summit in Hamburg, Germany on April 23rd. They have only a few tickets remaining if anyone wants to attend! tech-seo-summit.com
tech-seo-summit.com
February 12, 2026 at 2:07 PM
I’ll be giving a talk about Fonts and Web Perfomance at the Tech SEO Summit in Hamburg, Germany on April 23rd. They have only a few tickets remaining if anyone wants to attend! tech-seo-summit.com
A shocking 8.5% of sites that use CDNs deliver some static content directly to end users via cloud storage! Many are not compressing or caching this content either. This comes at a significant performance cost. Details, examples and @httparchive.org stats here - paulcalvano.com/2026-02-09-s...
February 9, 2026 at 12:34 PM
A shocking 8.5% of sites that use CDNs deliver some static content directly to end users via cloud storage! Many are not compressing or caching this content either. This comes at a significant performance cost. Details, examples and @httparchive.org stats here - paulcalvano.com/2026-02-09-s...
Tomorrow at 6pm the @nywebperf.com meetup is running another in person "Meet for Speed" session. We take requests from attendees for sites to do a webperf analysis on. @fastly.com is hosting us at their office in Union Square.
Have a site you'd like us to analyze? bit.ly/meet4speed-s...
Have a site you'd like us to analyze? bit.ly/meet4speed-s...
Join us for a Meet4SPEED session THIS THURSDAY, Jan 22 @ 6PM, in the @fastly.com Manhattan office.
Learn how to optimize sites with us!
RSVP: www.meetup.com/web-performa...
Have a site you'd like analyzed?
Submit here: bit.ly/meet4speed-s...
#webperformance #wpo #meetup #nyc
Learn how to optimize sites with us!
RSVP: www.meetup.com/web-performa...
Have a site you'd like analyzed?
Submit here: bit.ly/meet4speed-s...
#webperformance #wpo #meetup #nyc
[In-person] Meet for SPEED, Thu, Jan 22, 2026, 6:00 PM | Meetup
Join up for an opportunity to work together on optimizing our sites.
Have a site you'd like us to analyze? Add it here - [https://bit.ly/meet4speed-submit](https://bit.ly/
www.meetup.com
January 22, 2026 at 12:55 AM
Tomorrow at 6pm the @nywebperf.com meetup is running another in person "Meet for Speed" session. We take requests from attendees for sites to do a webperf analysis on. @fastly.com is hosting us at their office in Union Square.
Have a site you'd like us to analyze? bit.ly/meet4speed-s...
Have a site you'd like us to analyze? bit.ly/meet4speed-s...
Reposted by Paul Calvano
The 2025 Web Almanac by HTTP Archive has been officially released! 🚀
We would like to thank all of our contributors from around the globe who made this extensive report possible!
Check out the full report here: almanac.httparchive.org
We would like to thank all of our contributors from around the globe who made this extensive report possible!
Check out the full report here: almanac.httparchive.org
January 16, 2026 at 3:00 AM
The 2025 Web Almanac by HTTP Archive has been officially released! 🚀
We would like to thank all of our contributors from around the globe who made this extensive report possible!
Check out the full report here: almanac.httparchive.org
We would like to thank all of our contributors from around the globe who made this extensive report possible!
Check out the full report here: almanac.httparchive.org
My contribution to this years Web Performance Calendar is all about Third Parties and Single Points of Failure (SPOF). Based on @httparchive.org data I found that 67% of websites have at least 1 render blocking third party - and quite a few of them are SPOF risks!
Web Performance Calendar day 29 with @paulcalvano.bsky.social's research on 3rd parties, SPOF, and the need to test and monitor these. 67% of sites out there have at least 1 render-blocking external dependency.
calendar.perfplanet.com/2025/third-p...
calendar.perfplanet.com/2025/third-p...
Third Parties and Single Points of Failure
You've heard it many times - third party content can easily cause an otherwise well performing website to become sluggish and slow. And depending on how this content is loaded, it can also introduce s...
calendar.perfplanet.com
December 29, 2025 at 3:20 PM
My contribution to this years Web Performance Calendar is all about Third Parties and Single Points of Failure (SPOF). Based on @httparchive.org data I found that 67% of websites have at least 1 render blocking third party - and quite a few of them are SPOF risks!
New @httparchive.org analysis about sites adding AI Bots and Crawlers to their robots.txt files. While robots.txt doesn't "block" bots by itself, it's a clear demonstration of the preferences of site owners and the sentiment towards AI crawlers on today's web. paulcalvano.com/2025-08-21-a...
AI Bots and Robots.txt
There’s been a lot of discussion lately around AI crawlers and bots, which are used to train LLMs and/or fetch content on behalf of their users. In the past few weeks I’ve seen blog posts about the am...
paulcalvano.com
August 21, 2025 at 12:36 PM
New @httparchive.org analysis about sites adding AI Bots and Crawlers to their robots.txt files. While robots.txt doesn't "block" bots by itself, it's a clear demonstration of the preferences of site owners and the sentiment towards AI crawlers on today's web. paulcalvano.com/2025-08-21-a...
This Thursday at 6pm the NYC WebPerf Meetup is running another in person "Meet for Speed" session. We'll be taking requests from attendees for sites to do a web performance analysis on.
www.meetup.com/web-performa...
Have a site you'd like us to analyze? Add it here - bit.ly/meet4speed-s...
www.meetup.com/web-performa...
Have a site you'd like us to analyze? Add it here - bit.ly/meet4speed-s...
[In-person] Meet for SPEED, Thu, Jul 24, 2025, 6:00 PM | Meetup
Join up for an opportunity to work together on optimizing our sites.
Have a site you'd like us to analyze? Add it here - [https://bit.ly/meet4speed-submit](https://bit.ly/
www.meetup.com
July 21, 2025 at 8:04 PM
This Thursday at 6pm the NYC WebPerf Meetup is running another in person "Meet for Speed" session. We'll be taking requests from attendees for sites to do a web performance analysis on.
www.meetup.com/web-performa...
Have a site you'd like us to analyze? Add it here - bit.ly/meet4speed-s...
www.meetup.com/web-performa...
Have a site you'd like us to analyze? Add it here - bit.ly/meet4speed-s...
Tonight at 6pm the NYC WebPerf Meetup is running another in person "Meet for Speed" session. We'll be taking requests from attendees for sites to do a web performance analysis on. Fastly will be hosting us at their NYC office.
www.meetup.com/web-performa...
www.meetup.com/web-performa...
[In-person] Meet for SPEED, Thu, Dec 19, 2024, 6:00 PM | Meetup
Join up for an opportunity to work together on optimizing our sites.
Have a site you'd like us to analyze? Add it here - [https://bit.ly/meet4speed-submit](https://bit.ly/
www.meetup.com
December 19, 2024 at 4:00 PM
Tonight at 6pm the NYC WebPerf Meetup is running another in person "Meet for Speed" session. We'll be taking requests from attendees for sites to do a web performance analysis on. Fastly will be hosting us at their NYC office.
www.meetup.com/web-performa...
www.meetup.com/web-performa...
The video of my talk from the Performance Now conference in Amsterdam was posted today. #perfnow
The next #perfnow video is up: @paulcalvano.bsky.social with Performance Mistakes.
www.youtube.com/watch?v=j5E_...
www.youtube.com/watch?v=j5E_...
Performance Mistakes | Paul Calvano | performance.now() 2024
YouTube video by Web Conferences Amsterdam
www.youtube.com
December 18, 2024 at 1:18 AM
The video of my talk from the Performance Now conference in Amsterdam was posted today. #perfnow
This Friday afternoon I'll be at the Boston Web Performance meetup giving my talk on "Performance Mistakes". If you are in the Boston area and interested in web performance, join us!
www.meetup.com/boston-web-p...
www.meetup.com/boston-web-p...
Performance Mistakes, Fri, Dec 6, 2024, 4:30 PM | Meetup
December's meetup will feature Paul Calvano, on his return from the PerfNow conference in Amsterdam.
**Agenda**
* 4:30 pm: Arrive & networking
* 5:00 pm: Talk starts
* 5:
www.meetup.com
December 3, 2024 at 3:31 PM
This Friday afternoon I'll be at the Boston Web Performance meetup giving my talk on "Performance Mistakes". If you are in the Boston area and interested in web performance, join us!
www.meetup.com/boston-web-p...
www.meetup.com/boston-web-p...
Reposted by Paul Calvano
If you missed @paulcalvano.bsky.social at @perfnow.bsky.social, and happen to be in the Boston area next week, he'll be speaking at the Boston Web Performance December meetup.
Sign up on meetup: www.meetup.com/boston-web-p...
December 6th ∘ 4:30pm ∘ Akamai HQ in Cambridge.
#webperf #perfmatters
Sign up on meetup: www.meetup.com/boston-web-p...
December 6th ∘ 4:30pm ∘ Akamai HQ in Cambridge.
#webperf #perfmatters
Performance Mistakes, Fri, Dec 6, 2024, 4:30 PM | Meetup
December's meetup will feature Paul Calvano, on his return from the PerfNow conference in Amsterdam.
**Agenda**
* 4:30 pm: Arrive & networking
* 5:00 pm: Talk starts
* 5:
www.meetup.com
November 27, 2024 at 2:00 AM
If you missed @paulcalvano.bsky.social at @perfnow.bsky.social, and happen to be in the Boston area next week, he'll be speaking at the Boston Web Performance December meetup.
Sign up on meetup: www.meetup.com/boston-web-p...
December 6th ∘ 4:30pm ∘ Akamai HQ in Cambridge.
#webperf #perfmatters
Sign up on meetup: www.meetup.com/boston-web-p...
December 6th ∘ 4:30pm ∘ Akamai HQ in Cambridge.
#webperf #perfmatters
Last week I gave a talk at the #PerfNow conference titled “Performance Mistakes”. I started off explaining a bit about Etsy’s blameless culture, and how it’s ok to make mistakes. Then I shared 17 common #webperf mistakes using @httparchive.org data, with examples.
www.slideshare.net/slideshow/pe...
www.slideshare.net/slideshow/pe...
Performance Now '24- Performance Mistakes - Final.pdf
Performance Now '24- Performance Mistakes - Final.pdf - Download as a PDF or view online for free
www.slideshare.net
November 19, 2024 at 11:32 AM
Last week I gave a talk at the #PerfNow conference titled “Performance Mistakes”. I started off explaining a bit about Etsy’s blameless culture, and how it’s ok to make mistakes. Then I shared 17 common #webperf mistakes using @httparchive.org data, with examples.
www.slideshare.net/slideshow/pe...
www.slideshare.net/slideshow/pe...
Reposted by Paul Calvano
Great start to #perfnow this year with @tammyeverts.bsky.social and @csswizardry.com !
For those of you looking for the general web perf starter pack, here it is! Lots of new folks since last time I shared it
go.bsky.app/RVWSVqe
For those of you looking for the general web perf starter pack, here it is! Lots of new folks since last time I shared it
go.bsky.app/RVWSVqe
November 14, 2024 at 9:52 AM
Great start to #perfnow this year with @tammyeverts.bsky.social and @csswizardry.com !
For those of you looking for the general web perf starter pack, here it is! Lots of new folks since last time I shared it
go.bsky.app/RVWSVqe
For those of you looking for the general web perf starter pack, here it is! Lots of new folks since last time I shared it
go.bsky.app/RVWSVqe
Reposted by Paul Calvano
The all new performance chapter of the 2024 Web Almanac written by Jevgenija Zigisova and @inesakrap.bsky.social
almanac.httparchive.org/en/2024/perf...
almanac.httparchive.org/en/2024/perf...
Performance | 2024 | The Web Almanac by HTTP Archive
Performance chapter of the 2024 Web Almanac covering Core Web Vitals, with deep dives into the Largest Contentful Paint, Cumulative Layout Shift, and Interaction to Next Paint metrics and their diagno...
almanac.httparchive.org
November 12, 2024 at 12:46 AM
The all new performance chapter of the 2024 Web Almanac written by Jevgenija Zigisova and @inesakrap.bsky.social
almanac.httparchive.org/en/2024/perf...
almanac.httparchive.org/en/2024/perf...
Reposted by Paul Calvano
Fellow #perfnow attendee, the PerfPlanet advent calendar is looking for articles for the 2024 edition. Please come talk to me if you’re considering an idea for a post but you’re not sure and you need a second opinion calendar.perfplanet.com/contribute/
Contribute
Passionate about a topic? Working on a new tool? Have a technique you want to teach? Research you've done? Tell the web performance community!
Send your articles to ssttoo@ymail.com. Please include:
...
calendar.perfplanet.com
November 14, 2024 at 11:21 AM
Fellow #perfnow attendee, the PerfPlanet advent calendar is looking for articles for the 2024 edition. Please come talk to me if you’re considering an idea for a post but you’re not sure and you need a second opinion calendar.perfplanet.com/contribute/
Reposted by Paul Calvano
Took 2 mins at #PerfNow to talk about the RUM Community Group in W3C for anyone doing RUM. It's free and easy to join if you're interested! www.w3.org/community/ru...
November 14, 2024 at 2:01 PM
Took 2 mins at #PerfNow to talk about the RUM Community Group in W3C for anyone doing RUM. It's free and easy to join if you're interested! www.w3.org/community/ru...
Reposted by Paul Calvano
Yesterday during my #perfnow talk, I mentioned the Web Performance Slack. If you’d like to join the Slack, use this link before Nov 25: join.slack.com/t/webperf…
November 15, 2024 at 8:39 AM
Yesterday during my #perfnow talk, I mentioned the Web Performance Slack. If you’d like to join the Slack, use this link before Nov 25: join.slack.com/t/webperf…