The techniques Linear uses are not so much about backend performance and can be applicable for any client-server setup really. Not a JS/web specific problem.
But the industry is going the other way. Building frontends that try to hide slow backends and while doing that handling so much state (and visual fluff), that they get fatter and slower every day.
All to avoid writing a bit of JavaScript.
The bottleneck is not the roundtrip time. It is the bloated and inefficient frontend frameworks, and the insane architectures built around them.
Here's the creator of Datastar demonstrating a WebGL app being updated at 144FPS from the server: https://www.youtube.com/watch?v=0K71AyAF6E4&t=848
This is not magic. It's using standard web technologies (SSE), and a fast and efficient event processing system (NATS), all in a fraction of the size and complexity of modern web frameworks and stacks.
Sure, we can say that this is an ideal scenario, that the server is geographically close and that we can't escape the rules of physics, but there's a world of difference between a web UI updating at even 200ms, and the abysmal state of most modern web apps. The UX can be vastly improved by addressing the source of the bottleneck, starting by rethinking how web apps are built and deployed from first principles, which is what Datastar does.
The entire thing is a JavaFX app (i.e. desktop app), streaming DOM diffs to the browser to render its UI. Every click is processed server side (scrolling is client side). Yet it's actually one of the faster websites out there, at least for me. It looks and feels like a really fast and modern website, and the only time you know it's not the same thing is if you go offline or have bad connectivity.
If you have enough knowledge to efficiently use your database, like by using pipelining and stored procedures with DB enforced security, you can even let users run the whole GUI locally if they want to, and just have it do the underlying queries over the internet. So you get the best of both worlds.
There was a discussion yesterday on HN about the DOM and how it'd be possible to do better, but the blog post didn't propose anything concrete beyond simplifying and splitting layout out from styling in CSS. The nice thing about JavaFX is it's basically that post-DOM vision. You get a "DOM" of scene graph nodes that correspond to real UI elements you care about instead of a pile of divs, it's reactive in the Vue sense (you can bind any attribute to a lazily computed reactive expression or collection), it has CSS but a simplified version that fixes a lot of the problems with web CSS and so on and so forth.
Firefox mobile seems to think the entire page is a link. This means I can't highlight text for instance.
Clicking on things feels sluggish. The responses are fast, but still perceptible. Do we really need a delay for opening a hamburger menu?
> The entire thing is a JavaFX app (i.e. desktop app)
Besides, this discussion is not about whether or not a site is mobile-friendly.
You can use JavaFX to make mobile apps. So it's likely just that the authors haven't bothered to do a mobile friendly version.
So, like most of the non-first world? Hell, I'm in a smaller town/village next to my capital city for a month and internet connection is unreliable.
Having said that, the website was usable for me - I wouldn't say it's noticeably fast, but it was not show either.
On this site, every mouse move and scroll is sent to the server. This is an incredibly chatty site--like, way more than it needs to be to accomplish this. Check the websocket messages in Dev Tools and wave the mouse around. I suspect that can be improved to avoid constantly transmitting data while the user is reading. If/when mobile is supported, this behavior will be murder for battery life.
Many of us don't have to worry about this. My entire country is within 25ms RTT of an in-country server. I can include a dozen more countries within an 80ms RTT. Lots of businesses focus just on their country and that's profitable enough, so for them they never have to think about higher RTTs.