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Comment by ng12 | Hacker News Reader

Both of these sound like side-effects of trying to render massive amounts of UI artifacts that the user doesn't actually need or want to see. Whether you use JS+React or Rust+Yew you're going to get yourself into trouble with firehose-style data handling.

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Our users specifically demanded to see this much data. They actually complained that we couldn't show more. Once again you're making bold claims about a subset of use-cases that you clearly have no context for commentating on.

I never claimed that switching languages would have magically solved all our problems, but in our case it could've been a significant boon to performance which could've been one factor of many that contributed to a solution, and I just can't figure out why you have such a problem with that idea.

I'm an old 3d graphics programmer. One of performance rules is only render what will be displayed in that frame because rendering is expensive. That is why there are various culling algorithms, some are quite complicated. The reward for implementing all these advanced culling algorithms is very fast frame renders that give you more time to draw special effects, draw more characters, etc in a single frame.

I am a data engineer now and sometimes have to build web interfaces for scrolling large data tables. Just like in the 3d graphics world, the trick to responsiveness is culling. Only download and display the amount of data that the user will see at a given time, plus some overhead so the user never sees gaps when scrolling.

While Rust may have solved the problem in #1, it is unlikely to solve the problem in #2 because you are also fighting the network where Rust is useless. Need culling.

Unfortunately because web content is automatically positioned/sized in a way that's (mostly) opaque to JavaScript code, this is a pretty hair problem (compared to graphics where you have all the numbers on-hand). So most of the time you'd either have to a) try and replicate the math the layout engine ends up doing which makes things more brittle, or b) directly measure the computed dimensions/positions/visibility/scroll position of different elements, which tends to be a pretty large performance liability and in many cases would eliminate any gains you might receive.

There are some edge cases where these techniques can work - like if you have a really simple layout, and you can give a fixed-height to every item (table row or otherwise), and you assume the user is never going to resize their browser window - but it isn't nearly as obvious of a win as it is for 3D rendering and we just never decided it was worthwhile to try going down that rabbit-hole.

> Unfortunately because web content is automatically positioned/sized in a way that's (mostly) opaque to JavaScript code, this is a pretty hair problem (compared to graphics where you have all the numbers on-hand).

Exactly the same for 3d graphics. The auto-positioning is different but conceptual similar.

Yes B is my recommended approach. Since we are talking about performance, we should really be putting limits on what fast and slow mean. That is because it doesn't really matter if something is fast or slow, what matters is the performance difference between different approaches.

For B on average, performance will in the microsecond range, DOM rendering will be in the millisecond range, and the network is >100ms to seconds range. It is unlikely that B will be equal or slower to brute force rendering everything. Those X microseconds spent figuring out the culling window saves Y milliseconds rendering and saves Z milliseconds to seconds querying the network.

It's not that I have a problem with the idea, it's that I've spent most of the last decade building data visualization apps on the web and have never truly hit a wall with respect to JavaScript's performance characteristics. I think of it like this: no user is visually processing data faster than React can render it. If you render 300 elements and then want to render more updates before those first 300 had finished, did you need to render those first 300 at all? A human can't visually process hundreds of elements that quickly. The problem is that you're attempting to render a bunch of data that's not actually what your user is trying to see, not that React can't render it fast enough.

Most "performance" problems on the web are solved by simple techniques like virtualization, pagination, pushing expensive calculations to the server, avoiding round-trip requests, or basic UI/UX improvements. The only time I would care about JavaScript's actual runtime performance if I were doing something crazy like 3d rendering in the browser and that's a completely different set of problems than React or Yew are set up to handle.

The constraints on data visualization are not the same as the constraints on an IDE, which is closer to what we were building. Also, our users could definitely "process" the data faster than it could be rendered, because what they were doing most of the time was skimming through it for points of interest. They were not sitting and deeply considering each data point one at a time; they could glance at a page and know in a moment whether what they were looking for was there, or whether they needed to scroll further, or whether they needed to tweak the query and re-run it or click a link to a different screen. It was muscle-memory for them, and the tiniest hitch was frustrating to the user experience.

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