This sort of comment has completely lost the forest for the trees.You’re conflating scale with bloat. At large orgs the problem is that nobody is willing to step back and say “this sucks”. Trying to get this fixed involves getting 6 teams to agree upon something with no clear owner for the outcome and with everyone incentivised for not being blamed if one of the other groups tanks the effort.&gt; engineers should drop everything and work overtime on optimising performanceNo, we’re asking for it to be taken seriously by the organisation. I work in games, and on large projects we usually have a small team (2&#x2F;3 people of a team of 80-100) who are constantly working on this stuff. Their work is “subjective” improvements but often it’s just building tooling and telling other groups what they need to fix.

Isn&#x27;t this backwards? Optimizing assets becomes more important with scale, not less. Not saying it is actually prioritized that way or that it would be easy but IMO the more traffic you have the more important it is to be frugal with bits.

&gt; that amount of performance optimisation is usually not warranted at this scale.Indeed, you need to waste a few years hurting user experience before investing a few years into migration and writing another &quot;improved performance&quot; blog post.&gt; that engineers should drop everything and work overtime on optimizing performanceThe opposite, they should work less instead of more doing a worse job that results in scraping all their output later in a redesign

&quot;big company can&#x27;t make fast website&quot;nah

The beauty of functional CSS is that you can progressively transform everything. GitHub runs on entire modularized codebase, they can clean up the entire codebase within weeks, days if they use agents and see the effects of performance instantly.

The shitty team excuse.Performance is not complicated. You measure something and compare the numbers. Through my career I have encountered the following failures repeatedly:* The complete inability to measure things. This is common among people with low social intelligence. Many people in this line of work cannot measure things and form all kinds of bullshit excuses. Cannot do it all as if they are disabled. Sometimes it is laziness, sometimes it’s autism masking, and sometimes it’s stupidity&#x2F;ignorance where they believe they shouldn’t have to or are superior from convention alone.* The shitty team argument. It’s common for people to intentionally avoid or discard measures because there is fear superior performance may indicate an operating deficit. The last thing anybody in software wants is to change approach if they are on a shitty team, because corporate developers are allergic to training people. This is often justified by asking what happens if you work on a team or about new hires.* Throwing performance data away and lying about it. This is very common when performance data provides evidence that current conventions or favorite tools harm performance. If, for example querySelectors measure 100,000 times slower than some other approaches developers will pretend the performance evidence just doesn’t exist.* Guessing. When people suck at what they do they invent their own performance realities. When people guess at software performance they are supremely wrong more than 80% of the time and tend to be wrong by multiple orders of magnitude.

Yes, good points, but also with modern LLMs you can vendor the design system around and cut it to the bone on every app. If your organization ships a worse solution than Claude slop, do you really want to stick with it?

These type of comments often come from a place of arm-chair reasoning where you might not sit on the experience of working hands-on in a large team on a large product. While it’s probably true that X kB sufficient, that amount of performance optimisation is usually not warranted at this scale. Maintaining a design system, working with scoped classes, legacy code, and dealing with the complexities of chunking and probably further challenges we are not aware of from the outside. It seems like a common sentiment on HN (maybe not you in particular) is that engineers should drop everything and work overtime on optimizing performance, when it comes to web apps

FWIW, a very quick look at other comparable sites (what seems to be the main css files):sourcehut&#x27;s 128kb raw, and 28kb over the wire.codeberg is 420kb raw, and 66kb over the wire.

2.1MB is a huge most of the world where the internet speeds are not gigabyte etc. Yes, storage wise it&#x27;s not a lot, but it&#x27;s extra 5 seconds or so the user needs to wait for the site to load.

That shows a lot of disrespect for hardware that isn’t yours.

Read Performance Inequality Gap <a href="https:&#x2F;&#x2F;infrequently.org&#x2F;2025&#x2F;11&#x2F;performance-inequality-gap-2026&#x2F;" rel="nofollow">https:&#x2F;&#x2F;infrequently.org&#x2F;2025&#x2F;11&#x2F;performance-inequality-gap-...</a>

I don&#x27;t know how they perceive the performance. I see 41 network requests. That&#x27;s 2.1 MB of CSS over the wire, blocking rendering and hurting painting and loading speed. There&#x27;s 400 KB of Tailwind, 87 KB of general CSS, plus another 200 KB of other general CSS. They need to embrace functional CSS properly. I&#x27;m sure they could have a single CSS file under 80 KB that renders everything.

Yeah. It used to be unusable on mobile and great on desktop. But desktop has in my experience honestly been slipping pretty bad last few years. Maybe I live too far from the data center or something.One weird tangentially related thing is checking whether a PR is merge:able after solving a conflict in this repo[1] for some reason takes several minutes. Maybe because there are 1000 commits in the same file. Doesn&#x27;t seem UI related but weird regardless.[1] <a href="https:&#x2F;&#x2F;github.com&#x2F;MarginaliaSearch&#x2F;submit-site-to-marginalia-search" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;MarginaliaSearch&#x2F;submit-site-to-marginali...</a>

I&#x27;m still a bit salty they fiddled with the Lists UI when star&#x27;ing a repo and adding it to a list.The emojis I had at the beginning of the list name don&#x27;t render anymore (they show up as :eyesore_emoji_name: instead) and the list is sorted alphabetically now instead of by last modified. Also it&#x27;s one looong list instead of a small scroll-able container like it used to be.This is on Firefox btw. Now I&#x27;m seriously thinking about moving these GitHub &quot;bookmarks&quot; into a separate place like a bookmark manager even if I lose a bit of convenience.

Using GitHub everyday, I haven&#x27;t really noticed an improved performance. Actually i&#x27;d say pages are becoming slower. Browsing issues with many comments or big PR has a terrible experience as not everything gets loaded

Unfortunately the original blog post introducing the great CSS-in-JS system being removed is not in the &quot;Related posts&quot; section, would be nice to compare the thinking in the two

The improvement would be shipping human-readable structure to allow easier user overrides, not that hash abomination

Here&#x27;s a comparison using `brotli --best` on my app.<pre><code> 53K _long.css
 38K _short.css

 11K _long.css.br
 8.9K _short.css.br
</code></pre>
Both, dev and prod, have hashes because that&#x27;s part of what CSS Modules uses to avoid collisions.Besides download size, smaller names improve parsing speed too.

This.The only thing hashing classes achieves is making it difficult for users to use ad blockers and&#x2F;or custom CSS. I understand why e.g. Meta does it on their sites, but for GitHub it makes no sense.

Those class names surely gzip better than hashes over the wire?

Would you need a source map then for prod debugging?

Perhaps we should never ever use hashed class names?

There&#x27;s room for improvement still. Currently, the production build is using long-dev class names. e.g. `DirectoryContent-module__Box_3__gl6dE` could be compiled to a shorter hash like `gl6DE3a2`.If you use Vite:<pre><code> css: {
 modules: {
 generateScopedName: mode === &#x27;production&#x27;
 ? &#x27;[hash:base64:8]&#x27;
 : &#x27;[name]__[local]___[hash:base64:5]&#x27;,
 }
 }</code></pre>

You either &quot;improve performance&quot; or &quot;ship more ___&quot;, never both.

Sometimes, [GitHub] posts a [blog post in which they move away from] some terrible [way of doing things] I&#x27;ve never heard before, and it&#x27;s a weird indirect way to learn how awful their other [design choices] must be.<a href="https:&#x2F;&#x2F;xkcd.com&#x2F;2071&#x2F;" rel="nofollow">https:&#x2F;&#x2F;xkcd.com&#x2F;2071&#x2F;</a>

Once (like a year ago or so) stumbled upon some person&#x27;s post asking for someone to help them to &quot;fix&quot; some section at their website. It was done !important over !important over !important over !important. Said person was really convinced all it needed was another bunch of !important because apparently that was what ai spit for them, at least at that time

The performance must also improve because all iDevices on iOS &lt; 16.4 can no longer view GitHub in Safari due to old WebKit. I blame Apple for not allowing Webkit to be updated independently of the iOS firmware.Thankfully we now have the Reynard Browser (sideload&#x2F;trollstore) that uses GeckoView so supports more modern web standards.

At the cost of pretty bad build time performance when the application grows.
We migrated a &gt;1M LOC codebase to CSS Modules from VE for a ~30% build time speed improvement and much better tree shaking on Next.js

The Achilles heel of this class of library (including stylex, Linaria, etc.) is precedence. You either have to use a runtime and some complicated merging rules (e.g longhand overrides shorthand) or compile every possible combination of the styles at build time.

The idea of an `sx` prop kind of implies runtime. If there&#x27;s any logic in those objects it can&#x27;t be pre computed

It seems all the people criticising CSS in JS are doing it at runtime, like styled-component users.

I thought that whole point of CSS in JS was about building the CSS with JS in build time, to get managed and optimized output, who madman runs in in runtime?

Any time I see criticism of CSS in JS, and a move to CSS modules, I get sad they didn’t just do a bit more research. You can have both, while also not shipping any JS runtime for CSS in JS! And with TypeScript support.<a href="https:&#x2F;&#x2F;vanilla-extract.style&#x2F;" rel="nofollow">https:&#x2F;&#x2F;vanilla-extract.style&#x2F;</a>

And yet, there&#x27;s been a glaring overflow bug on every repo page if the repo has a sponsor button on Firefox Android for months.

Honestly, hats off to them. It&#x27;s hard to get anything done with Copilot so I&#x27;m amazed they even managed to do this.

css-in-js? Rofl. Whats next? Html-in-js?

Improving site performance by shipping more CSS