alt Hacker NewsA 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...
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V8 means javascript can be fast. However no amount of optimization can get around inefficient code. There is only so much optimizes can do about too many layers of abstraction, calculations that are used but not needed, and nested loops. Someone needs to step back once in a while and fix bottlenecks to make things fast.
It wasn't some dummy "add numbers" loop, this was doing math (multiply-add) on large 336-bit integers.
Performance sucked when I used native Javacsript BigInts. When I made my own BigInt by using an array of doubles, and pretended that the doubles were 48-bit integers, performance was much better. Using the arrays meant that all allocation of temporary values completely stopped. I had to write my own multiply-and-add function that would do bigint = bigint * 48-bit number + other bigint + other 48-bit number.