Ryan Townsend
@twnsnd.com
Technology Leader & Distinguished Software Engineer • 20+ YOE in Tech, 10+ as CTO • Public Speaker • LessonsofaCTO.com & TWNSND.com
Pinned
Ryan Townsend
@twnsnd.com
· Sep 24
Software Engineering Insight from 1990s PlayStation Game Development
YouTube video by Lessons of a CTO
youtu.be
This is a fun one: what a 1990s PlayStation game studio taught me about software engineering 🎮 youtu.be/86bnEALGiDY
Reposted by Ryan Townsend
December 31, 2025 at 8:29 PM
Put the NYE champagne down… my article is up on the 2025 Web Performance Calendar 🥳
Web Performance Calendar day 31 article 4/5: @twnsnd.com on Compression Dictionaries to dramatically shrink responses (60–90% smaller than Brotli/GZIP). Why adoption is slow. Practical architectural decisions and implementation tips to get huge bandwidth wins.
calendar.perfplanet.com/2025/from-th...
calendar.perfplanet.com/2025/from-th...
From Theory to Tiny: Implementing Compression Dictionaries
Compression Dictionary Transport became an official IETF Proposed Standard this September (congratulations to Yoav Weiss & Pat Meenan 🎉). If you don't know what they are, I recommend watching Pat's wo...
calendar.perfplanet.com
December 31, 2025 at 5:32 PM
Put the NYE champagne down… my article is up on the 2025 Web Performance Calendar 🥳
Wasted longer than I care to admit on trying to figure out why syntax highlighting was broken on my site only to discover it’s 1Password’s extension: www.1password.community/discussions/...
Apparently this has been around 2 weeks and it begs the question: why are they interfering with code blocks?!
Apparently this has been around 2 weeks and it begs the question: why are they interfering with code blocks?!
1Password Chrome extension is incorrectly manipulating <code> blocks | 1Password Community
The latest 1Password Chrome extension is incorrectly manipulating the DOM within <code> blocks on static pages. It looks it's using prism.js to try to...
www.1password.community
December 30, 2025 at 5:49 PM
Wasted longer than I care to admit on trying to figure out why syntax highlighting was broken on my site only to discover it’s 1Password’s extension: www.1password.community/discussions/...
Apparently this has been around 2 weeks and it begs the question: why are they interfering with code blocks?!
Apparently this has been around 2 weeks and it begs the question: why are they interfering with code blocks?!
TTFB has been around FOREVER as a #webperf metric, you'd think it would be well defined and well understood. @programmingart.bsky.social proves otherwise.
I loved reviewing this one: calendar.perfplanet.com/2025/ttfb-do...
I loved reviewing this one: calendar.perfplanet.com/2025/ttfb-do...
TTFB doesn't mean what you think it means
Time-To-First-Byte (TTFB) is a popular performance metric, yet there are many problems and nuances with it. Not only does it have several different definitions, it is usually also a "compound" metric,...
calendar.perfplanet.com
December 24, 2025 at 6:39 PM
TTFB has been around FOREVER as a #webperf metric, you'd think it would be well defined and well understood. @programmingart.bsky.social proves otherwise.
I loved reviewing this one: calendar.perfplanet.com/2025/ttfb-do...
I loved reviewing this one: calendar.perfplanet.com/2025/ttfb-do...
I’m using No-Vary-Search in production already—you probably should be too!
@tunetheweb.com has the details 👇🏻
@tunetheweb.com has the details 👇🏻
Web Performance Calendar day 23 with @tunetheweb.com on configuring caches to ignore non-content-affecting URL parameters and reclaim performance. No more of this query string = cache miss nonsense.
calendar.perfplanet.com/2025/fixing-...
calendar.perfplanet.com/2025/fixing-...
Fixing the URL params performance penalty
Tales of two pages…
What's the difference between these two pages?:
https://www.example.com/
https://www.example.com/?utm_source=email
I mean they've got different URLs, but many of us would ...
calendar.perfplanet.com
December 23, 2025 at 2:44 PM
I’m using No-Vary-Search in production already—you probably should be too!
@tunetheweb.com has the details 👇🏻
@tunetheweb.com has the details 👇🏻
This is huge for CSS loading performance.
Compression dictionaries are a little tricky to deploy today but totally worth the effort as the impact is enormous.
#webperf
Compression dictionaries are a little tricky to deploy today but totally worth the effort as the impact is enormous.
#webperf
Web Performance Calendar day 13 with Yoav Weiss (@yoav.ws) showing us a clever and creative way to ship *only* critical/necessary CSS for each page type (home, search, etc) while also avoiding duplicate code in the CSS bundles.
calendar.perfplanet.com/2025/how-to-...
calendar.perfplanet.com/2025/how-to-...
How to load CSS (fast)
Loading styles on the web is something that looks trivial at first.
You just add a <link rel=stylesheet> to your page (or <style> for inline styles) and you're done.
But if you wanted to load CSS fas...
calendar.perfplanet.com
December 13, 2025 at 2:32 PM
This is huge for CSS loading performance.
Compression dictionaries are a little tricky to deploy today but totally worth the effort as the impact is enormous.
#webperf
Compression dictionaries are a little tricky to deploy today but totally worth the effort as the impact is enormous.
#webperf
Incredible line-up for 2026's All Day Hey. Get your ticket 👉 ti.to/hey-presents...
With talks from an international line-up:
• Bramus Van Damme (Google)
• Léonie Watson (Tetra Logical)
• Fiona Safari (Tesco)
• Jake Archibald (Firefox)
• Alistair Shepherd (Series Eight)
• Cassie Evans (GSAP/Webflow)
• Phil Hawksworth (Deno)
ti.to/hey-presents...
• Bramus Van Damme (Google)
• Léonie Watson (Tetra Logical)
• Fiona Safari (Tesco)
• Jake Archibald (Firefox)
• Alistair Shepherd (Series Eight)
• Cassie Evans (GSAP/Webflow)
• Phil Hawksworth (Deno)
ti.to/hey-presents...
December 8, 2025 at 9:55 AM
Incredible line-up for 2026's All Day Hey. Get your ticket 👉 ti.to/hey-presents...
Hello from 3200m, -15°c
📍Les Deux Alpes glacier
📍Les Deux Alpes glacier
December 5, 2025 at 2:28 PM
Hello from 3200m, -15°c
📍Les Deux Alpes glacier
📍Les Deux Alpes glacier
OMG YES. This has been so needed.
Chrome 144 features a small change to #CSS overscroll-behavior: it now also works on non-scrollable scroll containers. While this change might seem trivial, it fixes an issue people have been dealing with for ages: prevent a page from scrolling while a
Use overscroll-behavior: contain to prevent a page from scrolling while a <dialog> is open
Chrome 144 features a small change to overscroll-behavior: it now also works on non-scrollable scrollers. While this change might seem trivial, it fixes an issue developers have dealing with for ages:...
www.bram.us
November 25, 2025 at 10:24 PM
OMG YES. This has been so needed.
Got my ticket to @pixelpioneers.co 2026 – early bird, student and diversity tickets are available now: pixelpioneers.co/events/brist...
Support your local/national events by buying early! ❤️
Support your local/national events by buying early! ❤️
Pixel Pioneers Bristol – 19 June 2026
An affordable one-day conference for front-end developers and UX/UI designers, featuring eight practical and inspiring talks delivered by world-class speakers.
pixelpioneers.co
November 25, 2025 at 1:18 PM
Got my ticket to @pixelpioneers.co 2026 – early bird, student and diversity tickets are available now: pixelpioneers.co/events/brist...
Support your local/national events by buying early! ❤️
Support your local/national events by buying early! ❤️
This is desperately needed on iOS.
On the Edge team, we think web apps should be easier to install.
The default browser install button is great, but we'd like something which you can use on your own site, how and when you want it.
That's why we're proposing the Web Install API, which you can now test!
The default browser install button is great, but we'd like something which you can use on your own site, how and when you want it.
That's why we're proposing the Web Install API, which you can now test!
The Web Install API is ready for testing
We're happy to announce that the Web Install API is now ready for testing on your own site, as an origin trial in Microsoft E
blogs.windows.com
November 24, 2025 at 5:29 PM
This is desperately needed on iOS.
Reposted by Ryan Townsend
The "i" in "iPhone" stands for "inequality", late 2025 edition:
November 18, 2025 at 3:51 AM
The "i" in "iPhone" stands for "inequality", late 2025 edition:
Implemented shared compression dictionaries [1] on an @11ty.dev site.
Nothing in production to share yet, but shows HTML responses being ¼–⅓ the size of @netlify.com's dynamic Brotli-compression.
~4-6kb per page inc. inlined CSS, before any tuning 🤯
[1]: chromestatus.com/feature/5124...
#webperf
Nothing in production to share yet, but shows HTML responses being ¼–⅓ the size of @netlify.com's dynamic Brotli-compression.
~4-6kb per page inc. inlined CSS, before any tuning 🤯
[1]: chromestatus.com/feature/5124...
#webperf
Chrome Platform Status
chromestatus.com
November 17, 2025 at 3:35 PM
Implemented shared compression dictionaries [1] on an @11ty.dev site.
Nothing in production to share yet, but shows HTML responses being ¼–⅓ the size of @netlify.com's dynamic Brotli-compression.
~4-6kb per page inc. inlined CSS, before any tuning 🤯
[1]: chromestatus.com/feature/5124...
#webperf
Nothing in production to share yet, but shows HTML responses being ¼–⅓ the size of @netlify.com's dynamic Brotli-compression.
~4-6kb per page inc. inlined CSS, before any tuning 🤯
[1]: chromestatus.com/feature/5124...
#webperf
Firefox 147 should land the Navigation API 🙌🏻 🙌🏻 🙌🏻 bugzilla.mozilla.org/show_bug.cgi...
1997962 - Ship Navigation API
RESOLVED (afarre) in Core - DOM: Navigation. Last updated 2025-11-13.
bugzilla.mozilla.org
November 13, 2025 at 7:31 PM
Firefox 147 should land the Navigation API 🙌🏻 🙌🏻 🙌🏻 bugzilla.mozilla.org/show_bug.cgi...
Reposted by Ryan Townsend
I can't describe how much I love this conference and how sad I am that this is the last one.
If you've ever thought it looks good and you want to try it, *now* is the time to do it with the cheapest tickets.
Trust me, you won't be disappointed. See you there?
If you've ever thought it looks good and you want to try it, *now* is the time to do it with the cheapest tickets.
Trust me, you won't be disappointed. See you there?
🚨 Announcing All Day Hey! 2026. Celebrating ten years of the conference. The final one. Let's go!
A curated conference for curious developers, designers, and technology leaders.
A curated conference for curious developers, designers, and technology leaders.
November 12, 2025 at 8:48 AM
I can't describe how much I love this conference and how sad I am that this is the last one.
If you've ever thought it looks good and you want to try it, *now* is the time to do it with the cheapest tickets.
Trust me, you won't be disappointed. See you there?
If you've ever thought it looks good and you want to try it, *now* is the time to do it with the cheapest tickets.
Trust me, you won't be disappointed. See you there?
Not only did @bram.us solve my problem (combining Scroll Driven Animations with @starting-style) but he even blogged about it 👏 All within 24 hours.
If I had one, my gratitude journal would mostly be a list of Bluesky handles 😅
If I had one, my gratitude journal would mostly be a list of Bluesky handles 😅
Blogged: www.bram.us/2025/11/06/c...
(There is still 1 part that has gotten me scratching my head myself … I’m hoping to get some clues from engineering on _why_ a certain thing is the way it is)
(There is still 1 part that has gotten me scratching my head myself … I’m hoping to get some clues from engineering on _why_ a certain thing is the way it is)
Combining Scroll-Driven Animations with @starting-style
How the cascade, the animation-fill-mode, and implicit keyframes make things a bit more complicated then you’d initially think …
www.bram.us
November 6, 2025 at 1:25 PM
Not only did @bram.us solve my problem (combining Scroll Driven Animations with @starting-style) but he even blogged about it 👏 All within 24 hours.
If I had one, my gratitude journal would mostly be a list of Bluesky handles 😅
If I had one, my gratitude journal would mostly be a list of Bluesky handles 😅
@bram.us is there any way to combine scroll driven animations with starting-style? e.g. to have something fade-in on page load with starting-style, but then have its scroll container apply an animation which operates on opacity?
I need the `@starting-style { opacity: 0 }` to take priority, I guess?
I need the `@starting-style { opacity: 0 }` to take priority, I guess?
November 4, 2025 at 10:46 PM
@bram.us is there any way to combine scroll driven animations with starting-style? e.g. to have something fade-in on page load with starting-style, but then have its scroll container apply an animation which operates on opacity?
I need the `@starting-style { opacity: 0 }` to take priority, I guess?
I need the `@starting-style { opacity: 0 }` to take priority, I guess?
When you have poor signal, the Bluesky app becomes more true to its name.
November 3, 2025 at 12:57 PM
When you have poor signal, the Bluesky app becomes more true to its name.
Reposted by Ryan Townsend
Fellow #perfnow fellows, a reminder that PerfPlanet calendar is coming this December for another edition. And it needs YOU. Please ask if you have any contribution ideas or concerns 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 [email protected]. Please include:
...
calendar.perfplanet.com
October 30, 2025 at 4:59 PM
Fellow #perfnow fellows, a reminder that PerfPlanet calendar is coming this December for another edition. And it needs YOU. Please ask if you have any contribution ideas or concerns calendar.perfplanet.com/contribute/
In my opinion, any SWE writing client-side JavaScript has a responsibility to understand the Event Loop.
@jakearchibald.com’s ‘In The Loop’ talk is required watching: www.youtube.com/watch?v=cCOL...
(cited by @andydavies.me at #perfnow)
@jakearchibald.com’s ‘In The Loop’ talk is required watching: www.youtube.com/watch?v=cCOL...
(cited by @andydavies.me at #perfnow)
October 31, 2025 at 9:24 AM
In my opinion, any SWE writing client-side JavaScript has a responsibility to understand the Event Loop.
@jakearchibald.com’s ‘In The Loop’ talk is required watching: www.youtube.com/watch?v=cCOL...
(cited by @andydavies.me at #perfnow)
@jakearchibald.com’s ‘In The Loop’ talk is required watching: www.youtube.com/watch?v=cCOL...
(cited by @andydavies.me at #perfnow)
“~200 bytes of JavaScript that can wreck your performance” – @andydavies.me explaining download size doesn’t always correlate to runtime performance at #perfnow
#webperf
#webperf
October 31, 2025 at 9:16 AM
“~200 bytes of JavaScript that can wreck your performance” – @andydavies.me explaining download size doesn’t always correlate to runtime performance at #perfnow
#webperf
#webperf
“What happens when you want to center a div in Chrome?” — @michael-hladky.bsky.social at #perfnow
This would make a great interview question that would give a variety of different answers.
#webperf
This would make a great interview question that would give a variety of different answers.
#webperf
October 30, 2025 at 11:33 AM
“What happens when you want to center a div in Chrome?” — @michael-hladky.bsky.social at #perfnow
This would make a great interview question that would give a variety of different answers.
#webperf
This would make a great interview question that would give a variety of different answers.
#webperf
Northern UK developers: join us tonight in Manchester for a talk on scaling to support hundreds of millions in client transaction volume.
It contains a lot of framework-agnostic advice, so non-Ruby developers stand to learn a thing or two too!
It contains a lot of framework-agnostic advice, so non-Ruby developers stand to learn a thing or two too!
October 16, 2025 at 10:34 AM
Northern UK developers: join us tonight in Manchester for a talk on scaling to support hundreds of millions in client transaction volume.
It contains a lot of framework-agnostic advice, so non-Ruby developers stand to learn a thing or two too!
It contains a lot of framework-agnostic advice, so non-Ruby developers stand to learn a thing or two too!
Safari TP 230 includes support for Largest Contentful Paint 🙌 #webperf
Webkit: Release Notes for Safari Technology Preview 230
Webkit: Release Notes for Safari Technology Preview 230
Webkit: Release Notes for Safari Technology Preview 230
webkit.org
October 15, 2025 at 9:27 PM
Safari TP 230 includes support for Largest Contentful Paint 🙌 #webperf