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by maga 1595 days ago
Yep, that's it. And the data marshalling overhead is even more pronounced with the native addon example (N-API Addon). But that's the thing, it's not "WASM always faster than JavaScript" as the author presents it. And on top of that, JS engines are no slouches either, you can optimize JS code to be pretty competitive in terms of performance even for computationally heavy tasks.

WASM is _predictively_ performant, being less subject to the vicissitudes of JIT, and offers better startup performance, allows for code reusability for existing C++/Rust code, but it's not a cure-all performance solution.
2 comments
dataangel 1595 days ago
It is pretty much always faster though. The same code completely written in JavaScript replaced by the same code written in Rust and compiled to WASM will nearly always be a speed up if you haven't screwed up and made the comparison apples to oranges by introducing copying or something like that. What's not always faster is mixing because of conversions. But this is just a reason to use more WASM :)
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peterth3 1595 days ago
The author isn’t saying it’s a “cure all performance solution.” The quote you copied uses cautious language like “almost always” and “results do vary.”

The author also cites real world apps that have switched to WASM and seen big performance gains (Figma and 1Password), which is much more compelling than the benchmarks you shared.

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maga 1595 days ago
You do realize that I didn't put up those benchmarks and wrote the article way back in 2017 just so that I can pick on a passage in this article? I was (and still am to a degree) excited about WASM, actually ported a significant chunk of my business logic from JS to C++ only to discover that the whole thing offered only ~20% performance boost, which didn't merit maintaining a whole separate toolchain. I'm not questioning the exciting results that Figma and such achieve, I'm saying that it's not "almost always" a case, and it's disingenuous to present it as such.
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peterth3 1594 days ago
I’m just noticing that my comment went from 5 points to 0 after your reply. I’m sorry if it was upsetting. Of course I know you are not the author of the benchmarks repo.

I made that comment in good faith pointing out that the author was not saying WASM is a catch all performance booster.

But I could get on board with your claim here that “almost always” is disingenuous (which wasn’t what you were saying in the previous comment).

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