Improving site performance by shipping more CSS
github.blog
github.blog
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/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.
For example:
> performance is not complicated
Not to mention all your assumptions about the motivations of people who don’t do optimization well. That one can’t possibly generalize.
Saying "Performance is not complicated" is not wrong. People and the systems set up for an application make it complicated. Its harder to check and verify.
I work in UI performance and the biggest thing slowing me down is always people
lol What? It's always amusing to me when someone makes absolute claims like "the industry" when having seen < 0.1% of it.
There are certainly plenty of performance problems that are not complicated, you're correct that many people do not have the skills necessary to solve even simple performance problems. The connection to social intelligence is a leap that doesn't really follow, though; this feels more like you just trying to dump on people who are missing skills, which isn't usually very helpful.
Regardless, however, there are absolutely performance problems that are complicated. When you're trying to optimize performance in environments constrained by compute, network, disk, and memory, finding the right solutions to reach the right optimum amongst the contributing factors can, in fact, be very much nontrivial. This is especially true if you're working on more general systems for which client use patterns may vary wildly.
Indeed, you need to waste a few years hurting user experience before investing a few years into migration and writing another "improved performance" blog post.
> that engineers should drop everything and work overtime on optimizing performance
The opposite, they should work less instead of more doing a worse job that results in scraping all their output later in a redesign
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.
> engineers should drop everything and work overtime on optimising performance
No, 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 (2/3 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.
If a decent portion of your audience literally cannot even play the game because its performance is too bad or it can't run on their hardware, then that immediately affects your bottom line. And at least until recently, you couldn't really push fixes for it once the game was delivered. And so I think at least a little bit of that mindfullness for performance has carried over to the modern day, though I will say that I do think that performance optimization does seem to subjectively be getting worse even in gaming.
In web dev, while it is true that it affects your bottom line, it's a little bit less obvious. And in the eyes of most management teams that's always something that can be prioritized later since you could always update it after you shipped a feature. Also, there was very much a culture of "the browser will handle it."
Not to mention, most devs are using the hardware that is many times better than their consumers.
There is a small, but very vocal group that complain about 30 vs 60fps, and yet there are games that push for 120/240 on consumer hardware (valorant and overwatch both run at very high frame rates on very low specs). As I said, it’s about prioritising it. _Why_ it’s being prioritised doesn’t really matter.
> also there was very much a culture of “the browser will handle it”
That is very clearly still the culture.
> most devs are using the hardware that is many times better than their consumers.
My last work PC was a 32 core 4GHz machine with 256GB RAM, a 4090, and 16TB of NVMe SSD’s with 10GB fibre. Our target platform was 9GB RAM, and an 8 core 1.1GHz processor, yet we still managed (just about).
To continue the comparison, cyberpunk can render night city in 16ms. Which makes me embarassed for GitHub that they can’t render a list of files and a static markdown readme in under a second.
Maybe some game devs talk like that behind closed doors, but don't think I ever saw it in public. Here the fig leaf usually is that "the average user doesn't care", as if they and not the most proficient users (if not developers with a clue) should be the yard stick.
With gaming the people who care the most, and know the most, will be heard by the gaming community even if the game devs try to ignore them, and most game devs know better than openly belittling that they care about details "most people wouldn't notice", or any of the stuff HN is filled with.
How about simply not making excuses anymore? Letting the criticism stand, sitting with it, letting it sink in and see what tomorrow brings? Why this need to akshually it?
nah
It is in fact really really really hard to keep things lean and performant over time as you support a more complex multi-purpose web app, but you still have to try. If you try hard enough - especially now in the age of pretty good agents - you can actually thread all of the different needles and keep (perceived and actual) latency low.
sourcehut's 128kb raw, and 28kb over the wire.
codeberg is 420kb raw, and 66kb over the wire.
And the bigger thing here is that this is all cached after it’s downloaded the first time.
Download speed isn't the only thing that matters
2MB of CSS just sounds insane. What are we even doing here?
FFS, why not just go back to explicitly inlining all the formatting in the HTML itself? I have trouble believing all the CSS is actively used. It’s not like any of this is written by humans these days.
2MB of text - isn’t that roughly half the size of the Christian Bible?
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't seem UI related but weird regardless.
[1] https://github.com/MarginaliaSearch/submit-site-to-marginali...
The emojis I had at the beginning of the list name don'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's one looong list instead of a small scroll-able container like it used to be.
This is on Firefox btw. Now I'm seriously thinking about moving these GitHub "bookmarks" into a separate place like a bookmark manager even if I lose a bit of convenience.
If you use Vite:
css: {
modules: {
generateScopedName: mode === 'production'
? '[hash:base64:8]'
: '[name]__[local]___[hash:base64:5]',
}
} 53K _long.css
38K _short.css
11K _long.css.br
8.9K _short.css.br
Besides download size, smaller names improve parsing speed too.
It also makes it much more difficult to create personal browser extensions as all css names are now unreadable.
Rudimentary experiment on https://github.githubassets.com/assets/te.1288ac5c9584fbf2.m... on replacing /(?<module>[A-Za-z0-9_-]+)__(?<local>[A-Za-z0-9_-]+)__(?<hash>[A-Za-z0-9_]{5})\b/:
${module}__${local}__${hash} (original): 72967 raw, 10993 br.
${module}__${local}: 68459 raw, 8867 br.
${hash}: 48754 raw, 8189 br.
${local}: 52610 raw, 7927 br. (Now in practice a few of these are likely to need disambiguation, so it’s probably a tad smaller than realistic.)
Frankly I think ${local} is the right target, with global disambiguation where necessary. For typical systems, I consider the hash approach to be foolish: its value is when interacting with unknown other styles, but when you’re compiling everything you should know everything, so you can disambiguate more selectively and succinctly/compressibly, as JS build tools like Rollup do (in flattening modules with colliding names, you’ll get Foo, Foo$1, Foo$2, &c.).
How?
---
Another approach is using base52 sequential names, such as `aa, ab, …`. I tried that a few years ago in Webpack, I don't remember but there was an issue, IIRC they weren't deterministic.
53K _long.css
11K _long.css.br
14K _long.css.zst
38K _short.css
8.9K _short.css.br
11K _short.css.zstThe only thing hashing classes achieves is making it difficult for users to use ad blockers and/or custom CSS. I understand why e.g. Meta does it on their sites, but for GitHub it makes no sense.
Thankfully we now have the Reynard Browser (sideload/trollstore) that uses GeckoView so supports more modern web standards.