> react has always been approx where it is now

Didn't know that. What I thought I knew is based on years of breathless claims about React's great performance. This is eye opening. Even Angular 8 does better in these benchmarks.

I think the breathless claims of performance are because for what React is doing -- storing the entire application tree using virtual DOM and seamlessly rendering updates -- it is really impressive. The fact that it is has similar performance as some much more naive frameworks is pretty amazing. In practice all of these frameworks are fast enough that you wouldn't notice unless you were doing something really crazy.

Yes, it's an admirable design. I've used it. I know. And no, nothing I've done with it has been intolerably slow. Although now I'm starting to wonder about some responsiveness issues I've experienced...

I also wonder if batteries care about elegance. Not really they don't. If one makes the highly likely assumption that these micro benchmarks are a measure of efficiency then it's actually difficult to do worse than React regarding battery life, heat, etc.

Very interesting.

Bundle size and start time are much more important metrics IMO unless you have a high perf use case. Like you said, most of these are fast enough for the majority of uses cases.

Then why are all the React-based web apps I use so slow?

Poor design and architecture. Doing too much and blocking the event loop, memory leaks, using too much frontend code to poorly mimic native browser features like new tabs and back buttons, uncaught exceptions that stop the javascript thread and leave the page stuck, etc.

React ecosystem is centered heavily on "components". This sounds nice, but IMO it breaks down quickly on the "whole program" level. What you end up with is crazy re-renders because it doesn't make sense to "componentize" the state.

It's probably not React itself. Most perceived performance issues I've encountered are due to architecture issues, usually relating to network calls.

i also asked this:

https://news.ycombinator.com/item?id=21357978

Facebook and Twitter are slow?

Facebook absolutely is, it's a beast. I find it can frequently freeze up my old laptop, which is admittedly getting past it but I have little trouble with most any other site.

I don't use Twitter, so can't comment.

Try mbasic.facebook.com

They are, I frequently stare at half-loaded UI on Facebook, and I'm using a fairly recent Macbook Pro.