Mastodawn

Jeb May 2, 2023

And now it’s riddle time! What will the following code print and when will the DOM change be actually painted to the screen?
Bonus question: what will change (if anything at all) if you resolve the promise in 30ms instead of 10ms?

#webperf #webdevelopment

Jeb Apr 27, 2023

Hey #webperf!
I have no idea why @ChromeDevTools have only x4/x6 CPU Throttling settings, but my M1 Mac is too damn fast to cause long tasks even with x6.
It was so annoying that I developed a little extension for this. Still a little buggy but does the job🤘.

Jeb Mar 15, 2023

We all know what `defer` attribute on <script> tag means.
"the script is downloaded in parallel to parsing the page, and executed after the page has finished parsing".
So we naively place this attribute on non-critical scripts.
And this might be a problem 👇 (1/6)
#webperf

Jeb Mar 13, 2023

Retweeting it again since there is one important thing I missed 🤦‍♂️.
You have to enable "Timeline: event initiators" experiment in DevTools Settings -> Experiments if you want it to work.
Once enabled you'll be able to see the arrow (and follow it to find the culprit).
#webperf
---
RT @malchata
This is a super cool little thing I found that was added recently to the performance profiler in Chrome DevTools. If you click on any "Recalcul…
https://twitter.com/malchata/status/1633847519720423426

Tweet / Twitter

Twitter

Jeb Feb 26, 2023

This alone was worth all the time I spent on this article.

1. If you enjoy someone's work - let them know, it's really incentivizing.
2. If you didn't read the article - give it a go, you might learn a few things about #webperf, #javascript and #webpack.

Jeb Feb 13, 2023

Love the statement 😅.
A nice read by @DebugBear on how @____lighthouse simulated network throttling compares to @ChromeDevTools and system-level throttling:
https://www.debugbear.com/blog/network-throttling-methods.

#webperf

Network Throttling: DevTools vs. Lighthouse vs. Netem | DebugBear

Synthetic testing tools throttle the network to simulate consumer devices. Learn how different network throttling methods impact the resulting performance metrics.

Show thread

Jeb Jan 26, 2023

So according to @addyosmani and this article https://web.dev/optimizing-content-efficiency-javascript-startup-optimization/ you should see it if you enable experimental feature `Timeline: V8 Runtime Call Stats on Timeline`. I did just that and nothing changed. Is this still a thing? Does it work for anyone else?

JavaScript Start-up Optimization

Keep your network transmission and parse/compile cost for JavaScript low to ensure pages get interactive quickly.

web.dev

Jeb Jan 26, 2023

Apparently, in @ChromeDevTools there is a way to break down the "Compile Code" phase into "Compile" and "Parse".
The only problem is that it doesn't work 😕.
#webperf

Jeb Jan 24, 2023

One of the most interesting findings about #webperf in Web Almanac 2022 is what percentage of websites will stop passing CWV assessment if (or should I say when) INP replaces FID.
That's... Intimidating🫢.
Using React? Better go fix some long tasks.

Jeb Jan 23, 2023

Working on something, guess what it is (obviously long tasks but what exactly?) 🙃
#webperf