Tim Kadlec
@tkadlec.bsky.social
Principal Product Manager @cloudflare—focused on performance and observability. Co-chair of https://perfnow.nl Taller than my photo looks.
My talk from last year's @perfnow.nl is now out. Come for the dad jokes & advice on how to troll your kids, stay for my thoughts on stubborn empathy for our users as the foundation for web perf & two threats to the web: the monoculture and the machine. www.youtube.com/watch?v=Dvpi...
Stubborn Empathy - Tim Kadlec - performance.now() 2025
YouTube video by Web Conferences Amsterdam
youtube.com
Six early-bird tickets left. Will they run out today? Or are you feeling lucky and wait for Monday? perfnow.nl/tickets.html
performance.now(); 19th and 20th of November 2026, Amsterdam
On 19th and 20th of November 2026, the seventh edition of performance.now() will take place in Amsterdam—a single track conference, covering today’s most important web performance insights.
perfnow.nl
Ticket sales are open! perfnow.nl/tickets.html
performance.now(); 19th and 20th of November 2026, Amsterdam
On 19th and 20th of November 2026, the seventh edition of performance.now() will take place in Amsterdam—a single track conference, covering today’s most important web performance insights.
perfnow.nl
📝 New post: Losing Focus timkadlec.com/remembers/20... Expressing some concerns I have about how all the AI-buzz is causing our industry to lose focus on what matters: the actual human beings using what we build.
I wrote "Your Voice" in 2016 to encourage people new to speaking & writing to be yourself, to find what's authentic for you and make sure you let that shine through in what you create. Seeing so many social posts and blog posts clearly written by AI—it feels more important today than 10 years ago.
Your Voice - Web Performance Consulting | TimKadlec.com
timkadlec.com
I'm very excited about this! Have seen some really significant impact in our tests. With the sizes of websites and JS payloads continuing to increase, this is both important and impactful.
Cloudflare@cloudflare.social · 4mo agoToday, we’re excited to give you a sneak peek of our support for shared compression dictionaries, show you how it improves page load times, and reveal when you’ll be able to try the beta yourself. https://cfl.re/42egXfC
Really excited to see the support for compression dictionaries that @cloudflare.social is working on. Great background on the feature as well.
Cloudflare@cloudflare.social · 4mo agoToday, we’re excited to give you a sneak peek of our support for shared compression dictionaries, show you how it improves page load times, and reveal when you’ll be able to try the beta yourself. https://cfl.re/42egXfC
p75 and p90 JavaScript bytes on the web have exploded since May, 2025—easily the largest 10 month period based on HTTP Archive data since 2023. The long-tail is getting worse, very quickly. Gemini, what happened in May 2025?
Doing my part to keep customer support people employed and paid one annoying and frustrated "please let me talk to a real person and never make me use this useless AI support again" message at a time.
The somewhat ironic part about all the backlog of code to review thanks to AI coding tools is that AI is _significantly_ better at code review than it is at code generation.
Live view of me waiting for this day... Gonna be a lot of fun with some awesome stuff to come!
a small brown and white puppy is standing on a tiled floor .
ALT: a small brown and white puppy is standing on a tiled floor .
media.tenor.com
Ryan Townsend@twnsnd.com · 5mo agoSuper excited to announce today I joined @cloudflare.social as a Principal Product Manager to work on RUM & Web Analytics with the Speed team! 🏎️💨 Buzzing to be working with @tkadlec.bsky.social and @sergeyche.dev, among many other fantastic folk 🙌
Do I know anyone, or does anyone I know know anyone, at eBay who I can chat with about some things I'm running into with their API's?
AI automated support bots are one of the worst plagues to infest the internet. They are truly awful, infuriating and useless 95% of the time. Please, I am begging, just let me talk to a real person.
AI will have to pry em dashes out of my cold dead hands Interesting conversation I had with my kids recently: my high-school daughters actively avoid using "big" words in their writing because they get accused of using ChatGPT. Literally dumbing down their writing to avoid being accused of using AI
Sarah Drasner@sarahedo.bsky.social · 7mo agoI write my posts myself, not with AI. I had to take all the em dashes out because I was too worried people would think it AI generated 😔
I do firmly believe that if you're an individual or company that is NOT over-indexing on AI right now, you have the competitive advantage. Unfortunately I do not have high hopes that the industry will recognize that until significant damage has been done.
Minovsky@minovskyarticle.bsky.social · 8mo agoThe handmade, human qualities of your work are more valuable than they've ever been. Don't doubt that for a second.
Very happy to work on a tool like that with @tkadlec.bsky.social and the team! Please try it out and post the issues and PRs.
Tim Kadlec@tkadlec.bsky.social · 9mo agoTelescope, the new cross-browser performance testing agent I mentioned at #perfnow that we @cloudflare.social have open-sourced is here: github.com/cloudflare/t... We want this to be a tool the entire community is able to contribute to and benefit from, so please help us make it better!
At the airport heading back after another incredible #perfnow. Each year, I'm reminded of how fortunate I am to be a part of the performance community. So many wonderful, kind, smart people all working together to make the web better. Already looking forward to next year.
performance.now() 2026 will take place on 19th and 20th of November 2026. #perfnow.
Telescope, the new cross-browser performance testing agent I mentioned at #perfnow that we @cloudflare.social have open-sourced is here: github.com/cloudflare/t... We want this to be a tool the entire community is able to contribute to and benefit from, so please help us make it better!
GitHub - cloudflare/telescope: Cross-browser web performance testing agent
Cross-browser web performance testing agent. Contribute to cloudflare/telescope development by creating an account on GitHub.
github.com
I appreciate everyone at #perfnow letting me have my "old man yells at cloud" moment this morning. Slides are now up: noti.st/tkadlec/3imH...
Stubborn Empathy by Tim Kadlec
One of the most important roles we play on the web is as the users line of defense, which requires that we demonstrate stubborn empathy on their behalf. Unfortunately, that concept is all too easy to ...
noti.st
I have been sooooo looking forward to this! SPA heuristics are gonna be such a huge step forward for measuring perf on the web and finally having hard data on the perf impact. @mmocny.com #perfnow
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 ssttoo@ymail.com. Please include: ...
calendar.perfplanet.com
“We should treat accessibility as something that is structural or baked in or part of the DNA, if we want to be successful” — says @marcysutton.com at #perfnow “Don’t treat it like trying to put chocolate chips into a cookie after it is baked” I love this framing!
Slides from my @perfnow.nl talk — How Fast Is Fast Enough? — are up! If you’re at #PerfNow (or even if you’re not) I’d love to talk about creating a delightful experience for your users. speakerdeck.com/tammyeverts/...
How Fast Is Fast Enough? [PerfNow 2025]
It sounds like a simple question, but if you've been working in web performance long enough, you know the answer is far from straightforward. In this ke…
speakerdeck.com
