alt Hacker NewsI actually compared WASM to Javascript for a particular integer-math-heavy task. For a single run, Javascript beat out WASM because WASM had a lot more setup time. After running both 1000 times, they were almost equal in runtime.
Yes, even though the Javascript was written using Doubles and the WASM was written using 64 bit ints. It just means that it's possible to write optimized Javascript (mainly by reducing object allocations, reuse objects instead)
Replies
eska • last Friday at 3:09 AM
Your mental model of integer vs double performance sounds outdated by decades. I’d suggest reading up on instruction performance on agnerfog, should be eye opening.
A benchmark of adding numbers doesn’t tell you how it performs on real world websites and codebases. I wouldn’t be surprised if JavaScript was still very competitive, simply because of how good V8 is, but I don’t think we can conclude anything from your benchmark.
Of course it is always possible to write highly optimised code. But that’s not what people actually do, because of time, skill and maintenance constraints. Here’s a case study: in 2018 Mozilla ported some code from JS to Rust + WASM and got a 6x speed up [1]. An expert in V8 responded to this with highly optimised JavaScript, saying Maybe you don't need Rust and WASM to speed up your JS [2]. Both articles are worth reading! But it is worth remembering that it’s a lot quicker and easier to write the code in #1 than #2 and it is easier to maintain as well.
[1] - https://hacks.mozilla.org/2018/01/oxidizing-source-maps-with...
[2] - https://mrale.ph/blog/2018/02/03/maybe-you-dont-need-rust-to...