While I don't have the performance bottleneck numbers of React, I don't think it's about Javascript vs. WASM here.

I've seen/built some large Qt/QML applications with so much javascript and they all performed much better than your average React webapp. In fact the V8 / other browser Javascript engines also have JIT while the QML engine didn't.

Comparing QtQuick/QML + JS to HTML + JS - both GPU accelerated scenegraphs, you should get similar performance in both. But in reality it is rarely the case. I suspect it might be the whole document oriented text layout and css rules, along with React using a virtual DOM and a lot of other dependencies to give us an abstraction layer.

I'd love to know more about this from someone who did an in depth profiling of the same/similar apps on something like QtQuick vs. React.

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wmf 7 hours ago | parent [-]

It's not about Javascript vs. WASM; it's the DOM. DOMless apps like Figma are much faster.

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esprehn 6 hours ago | parent [-]

The slowness in a React app is not the DOM. Typical apps spend most of their time running component code long before any DOM mutations are committed.

If you look at DOM benchmarks it's extremely fast. Slow web pages come from slow layers on top.

	▲	leptons 2 hours ago \| parent [-]
		It depends on the app. If the app has many hundreds or even thousands of DOM elements, there's no way to make that work smoothly with React or any other library or framework. Then a canvas based solution can fix things. I know, I've had to fix slow React apps.