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Comment by journey_16162 | Hacker News Reader

As a front-end developer, I can't help but notice how much useless computation is going on in a fairly popular library - Redux. It's a store of items, if just one tiny items change in the whole store, every subscriber of every item gets notified and a compare function is ran to check if it changes. Perhaps I'm misunderstanding something and not to bash on Redux - I'm sure there are well-deserved reasons it got popular, but to me that just sounds insane and the fact that it got so much widespread adoption perfectly reflects how little care about performance is given nowadays.

I don't use a high-end laptop and I'm not eager to upgrade is because I can relate to the average user of the software I develop. I saw plenty of popular web apps feeling really sluggish.

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>I don't use a high-end laptop and I'm not eager to upgrade is because I can relate to the average user of the software I develop.

Thank you so so much. It's insane how it feels like the speed of much of our software hasn't improved or even regressed despite the gigantic advancements made over the years. People really don't seem to care about this.

I had an argument about it with a senior colleague regarding some industry software. He figured it wasn't worthwhile to improve the speed of some table fetching and calculations that people actually had to wait on since it would only amount to a bit more than a second or so on top of the regular slowness of it all.

A second that had been multiplied on at least 20 pc's each going trough it at least a 100 times a day of more than 260 times each year over at least 10 years so far. Turns out more than 5 million seconds is a lot of man-hours which whilst cheaper than ours amount to manyfold what it would have taken to fix it.

Hi, I believe I understand you. If you look at immutable data structures implemented using JS primitives, it will surely look terrible. However, there's a lot of benefit to using a FP approach like Redux.

It's much easier to reason about state updates if all you have is pure functions. It allows you avoid very annoying and hard to catch bugs. I've seen this personally, when replacing a spaghetti component with a straightforward `useReducer` hook.

Unfortunately, we don't really have a performant way to express this pattern in JS (or even in other languages?). You could use something like elm-lang, but it's not as widespread.

Right it’s basically just developer convenience.

So from your post it follows that if a developer can reason about the state changes of their app without redux, they should do so if there are performance concerns. Right?

I say this as a webdev who has written pure vanilla Js SPAs a decade ago, and someone who often uses Redux now on most projects today. So I know it’s totally possible to have performant mutable state management on a project that isn’t a mess - that’s how we always did stuff before redux.

> if a developer can reason about the state changes of their app without redux, they should do so if there are performance concerns. Right?

That is correct :)

However, I'm not sure how many developers will be able to maintain the project and keep the invariants implicitly ingrained in the codebase by the smart developer who can reason about mutable state changes.

I would say that the tool should reason about it at compile time, a la SolidJS.

Can SolidJS reason about collections of items being added and removed? My pseudo-reactive Qt apps do well with structs, but I often resort to recomputing the entire list of items when elements are added or removed (because QAbstractItemModel is hell to work with, and because my "move items" commands are not exposed to the GUI layer). Perhaps even diffing the item list would be faster than telling the GUI that all data was changed. (Though with <100 items, it really doesn't matter.)

I don't know how item lists are handled by GTK3, GTK4 (which is supposedly a lot better: https://blogs.gnome.org/antoniof/2022/06/15/the-tree-view-is...), Svelte, Solid, or the C# GUI frameworks.

I think developer speed is more important than optimising clock cycles unnecessarily. Generally writing to dom is much much slower than evaluting a few thousand expressions.

For the cases when it's not, use memo.

> I think developer speed is more important than optimising clock cycles unnecessarily.

Developer time is spent once. Users will always have to pay the price of additional run time. For. Each. Single. User. Always.

It scales!

Due to the scale of, e.g. slow front-ends, with millions of users, this takes a HUGE amount of time. Only to save a few hours or days to develop it better.

Having 1 million users each wait a single second is already 11 days. If they have to wait that single second for each interaction, it quickly adds up.

It is also bad for the environment due to scaled up inefficiency and resulting increase of power usage.

Although I 100% agree with you, the problem is that these costs don't affect the original developer; it is an externality; a lot like carbon pollution. It's cheaper for the organisation to optimise for developer speed, even if the cost of that is borne by all the users.

> Having 1 million users each wait a single second is already 11 days.

This will sound like a nitpick, but it's actually worse. 1 million users waiting a single second is 11,000,000 seconds, right? A day has 86,400 seconds. 11 million divided by 86k is 127.31.

That means million users combined just spent 127 days and 8 hours because of the "just one second" delay.

Ah that's what happens when I don't have my cup of coffee in the morning. I went from 1 to 11 million in a typo and didn't even reason. So yeah, it was 12,7 days, not 127. Guess I'll double check having my coffee next time I'm doing back-of-the-napkin math /facepalm

I’m not claiming that we should not improve that single second, but summing it is a meaningless operation. It doesn’t matter for a user how many other user spent time on it as well.

Redux is not a new pattern. The pattern is many decades old. The reason we use it now is because computers have become fast enough that it's okay now. Nobody thinks this is a performant pattern; it's only "new" because of how terrible the performance is. This is offset by how easy it is to use. All of this also applies to React and Vue.

blaming popular webapps being sluggish after spending a whole paragraph on Redux is a bit of a non sequitur imo. performance issues are multicausal, i hope you can separate criticism of one library from emergent properties of complete products

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