Two screenshots from Chrome DevTools side-by-side. On the left it says "Before" and shows that rendering took 1518 milliseconds. On the right it says "After" and shows that rendering took 610 milliseconds.

Here's your friendly reminder that CSS selectors are global and evaluated RTL, so if you have selectors that are very broad like `.container > div` you might be impacting performance in a measurable way 🙈

Before and after profile of server switching after some selector optimizations in @discord.com

Integration tests are best tests Itegration tests are the most important kind of tests. You should strive for excellent integration test coverage and invest relatively little time in unit tests. I've believed this since I worked on c...

New blog post, with a perhaps mildly unpopular opinion: jayconrod.com/posts/133/in...

I don’t hate it.

But I’d still probably stick to UUIDs because it’s standardised which lets random services work together without much thinking e.g. Postgres UUID type at least gives me free validation and storage optimizations regardless of what app generates the ID and so on…

What are better alternatives that people should switch to?

Progress on TypeScript 7 - December 2025 - TypeScript Earlier this year, the TypeScript team announced that we’ve been porting the compiler and language service to native code to take advantage of better raw performance, memory usage, and parallelism. Th...

We've got some updates on TypeScript 7! The new native port

- can type-check any project
- supports --build and --incremental
- has rich editor features implemented
- is still 10x faster

and is ready for you to try today!

devblogs.microsoft.com/typescript/p...

GitHub - ayuhito/modern-tar: 🗄 Zero dependency streaming tar parser and writer for every JavaScript runtime. 🗄 Zero dependency streaming tar parser and writer for every JavaScript runtime. - ayuhito/modern-tar

Just cut another release for modern-tar.

I’ve been benchmarking it a bunch and it seems like we’re the fastest Node.js tar library on all benchmarks.

Especially in a big way for many small files which are typical for node_modules like directories 🚀

[DEP0169] DeprecationWarning: `url.parse()` b̶͎͆e̴̛̟͖͠havior is not standardized and̴̃͜ ̷͈̤̿͠p̴͔̉͊rone to errors that hav̶̧̗̄̂e security impl̶̖̗̎͒ï̵̩͈c̸̢̑̍a̶̫̝͝t̴̖̒i̵̛̲͙̓ő̵̩̣̚n̴̰̏s. Use the Ẃ̷̯̬̟̫͉̠̞̬̣̃̀̀̒͒͊̓̍́H̷̙͇͇̞̘̝͍̣͍̲̼̕̕̚͜A̶̺͇͒Ţ̴̠͍̻̯̮̬͇͍̈͐̆͗W̶̪͈̤͊́͑̀͜͜G̷͇͒̋̿̾̔̌̾͊͘͝͝͝ URL API instead. C̸͍̤̥̲̩̣̭̈͒̉̅̓͑͋̋͆̋̾͐̃V̴̦̖͚̥̘̲̦̺̣͌̎̒͌̅̊É̶̼̟̈́͛̋̿̈́͛̕s are not issued for `url.parse()` v̶̘͔͎͚͔̩̻̰̌͋͂͊̕͝ư̷̻͋͗͌̽́̓̂̋̅̓ḽ̶̢̳̥̗̯̻̳̜͉́̇͝͝n̴̬̆̀͂͂͛͘͘͝͝͠ë̴̯̺͎͉͇̝͂̅̍̀͌̽͂͐́̏̚ͅŗ̷̢̥̮͚̩͕̬̳̹̫͎̝̹̑̾͛͐͌̅̂̌͛́͒̚̚͝͝ͅḁ̷̡͇͙͓̺̮̥̠͉̪̤͆̉̽̆̆́͠b̶̢̲̯̼̭͖̖̳̲̘̫̫̳̳͔͂̃̾͐͐̏̔͆̎́̚̕͜͠i̵̹͍͔̟̞̲̫̪͍̽͋̔͑ļ̷̢͔̬̫̫͔̤͇̮̙̌̊̿͋̂͛̉̾͜i̵̢̘̜͚̺̬̊́̽̔̓̈́͊t̵͕̗̲̖̟͕͕͉̞͕̞̜͚͒̿͐͜ͅi̶̤̖̥̥̺͋̎͛͊̐̌͑͐̋̓̚̕͝ͅe̸̪̖͒̈́̾ş̴̨̢̖͓͚͎͇̣̥͓̣̤̪̜͐͗̃̏̓ͅ.

Community Showcase (Q3 2025) An update on what the community have been up to in Q3 of 2025

here's what the @e18e.dev community has been upto for the last couple of months!

huge thanks to everyone involved 🎉 much more to come very soon, and we have a roadmap of some super useful tools in the works

I’ve read your blog posts many on sustaining yourself as a FT OSS developer which was inspiring, but alas you deserve more. Congrats!

One of the more awesome blog posts by the Go team that simplified a not so simple topic really well!

A picture of a foggy street

Edinburgh castle failing to render, likely thanks to the AWS outage

Unpacking Cloudflare Workers CPU Performance Benchmarks Cloudflare investigated CPU performance benchmark results for Workers, uncovering and fixing issues in infrastructure, V8 garbage collection, and OpenNext optimizations. These improvements have made C...

Cloudflare investigated performance benchmark results for Workers, uncovering and fixing issues, making Workers faster for all customers.

blog.cloudflare.com/unpacking-cloudflare-wor...

How we found a bug in Go's arm64 compiler 84 million requests a second means even rare bugs appear often. We'll reveal how we discovered a race condition in the Go arm64 compiler and got it fixed.

84 million requests a second means even rare bugs appear often. We'll reveal how we discovered a race condition in the Go arm64 compiler and got it fixed. https://cfl.re/3WrpKrB

New architecture makes a centralised interface that only accepts Uint8Array chunks which allows us to skip converting between streams entirely 👾

GitHub - ayuhito/modern-tar: 🗄 Zero dependency streaming tar parser and writer for every JavaScript runtime. 🗄 Zero dependency streaming tar parser and writer for every JavaScript runtime. - ayuhito/modern-tar

Released v0.4.0 of modern-tar today! Huge performance improvements and a new architecture.

We originally converted Web Streams into Node Streams to make maintaining cross compatibility manageable… but synchronising those two felt very incomplete and was prone to so so many race conditions 👾

VoidZero's 2025 Open Source Pledge Report VoidZero is continuing our commitment to the Open Source Pledge and donating $48,360 or $3,454 per VoidZero developer to external open source projects

The world depends on Open Source software

After joining the @opensourcepledge.com last year, we are increasing our annual commitment to $48,360 for 2025.

Take a look at our full 2025 report on which vital projects we're sponsoring and how the money is distributed.

voidzero.dev/posts/oss-pl...

Fun little Go compiler CL merged today: go.dev/cl/706655

Uninlined generic functions have a "dict" arg, since Go generics are neither erased nor monomorphized, but instead instantiated for each "GC shape" (e.g. T=*int and T=*float64 get the same code, but T=int32 and T=int64 do not).

It’s hard to express how I love working with Go in my day job and wouldn’t want anything else, but could not say the same for JavaScript.

But I absolutely enjoy working with JavaScript as a hobby, whilst Go feels a little bit more like a chore.

Both communities are 🔥 though

I didn’t expect the savings to be that great! Glad it worked out!

packagephobia.com results for the `@bluwy/giget-core` package, showing a sharp decrease in install size in its latest 0.1.4 version

`@bluwy/giget-core` is now back to a small 90kB install size thanks to @ayuhito.com's `modern-tar` package! Perf is also slightly faster.

Eliminating Cold Starts 2: shard and conquer Earlier this month, we finished deploying a new technique intended to keep pushing the boundary on cold start reduction.

We reduced Cloudflare Workers cold starts by 10x by optimistically routing to servers with already-loaded Workers. Learn how we did it here. https://cfl.re/3Kf8PGa #BirthdayWeek

I’ll look into it!

I don’t expect it to be faster at all as some alternatives use specialised dependencies to replace Node streams entirely. But I also don’t believe the difference is significant.

GitHub - ayuhito/modern-tar: 🗄 Zero dependency streaming tar parser and writer for every JavaScript runtime. 🗄 Zero dependency streaming tar parser and writer for every JavaScript runtime. - ayuhito/modern-tar

🗄️ modern-tar

I just released a new zero dependency streaming tar parser and writer that is built with the browser-native Web Streams API!

Please check it out! It's awesome 📼

github.com/ayuhito/mode...

New blog post, reflecting on nearly seven years since the Firecracker launch, and how we're using Firecracker to power serverless databases (in Aurora DSQL) and infrastructure for AI agents (in Bedrock AgentCore).

Here's the post: brooker.co.za/blog/2025/09...

Rolldown v1.0.0-beta.39 has been released!

⚡ macOS Performance Boost: 10%-30% faster bundling, up to 45% in extreme cases.

🎯 Cross-Chunk Optimization: Support for __NO_SIDE_EFFECTS__ annotation, as well as
better tree-shaking across module boundaries and more efficient DCE

one of the most common issues is inconsistencies in builds due to the weaknesses of scraping

Google Fonts is incredibly dynamic serving completely different files depending on your useragent, so often there are tradeoffs that lead to worse situations for one type of user over another

feat(core): new package by ayuhito · Pull Request #1079 · fontsource/fontsource Related: #39, #588, #728, #730, #773, #792, #908, #929, #984, #989, #990, #1036, #1050 and maybe more. This is an initial implementation of an experimental package that will build Google Fonts from...

really excited to merge this PR that enables Fontsource to build fonts from source rather than scraping all of Google Fonts

if it works out, it lets us close tons of issues and even makes reaching the fabled zero issues repo a realistic goal!

🚀 Coming Soon: OpenID Connect (OIDC) Support for npm Registry · community · Discussion #161015 Hello npm community! 👋 We're excited to announce that we're bringing OpenID Connect (OIDC) authentication to the npm registry! This new feature will enable more secure, token-less authentication fo...

some npm folks might be looking into scope based solutions

Wasm 3.0 Completed - WebAssembly WebAssembly (abbreviated Wasm) is a binary instruction format for a stack-based virtual machine. Wasm is designed as a portable compilation target for programming languages, enabling deployment on the...

The WebAssembly 3.0 spec is complete!

webassembly.org/news/2025-09...

This includes major features like GC, 64-bit memories, exceptions, and tail calls.

Midnight shower thought - I wonder if we could leverage the AST in tsgo and transpile the code into an equivalent Go AST?

With a ready to use GC and a packed standard library for I/O, I wonder if JS->Go native could be a thing.

(There’s definitely limitations, but it could be worth it)