Poor BigInt Performance in Bun compared to other runtimes

[tshmieldev]

What version of Bun is running?

1.2.23, 1.3

What platform is your computer?

Darwin 23.3.0 arm64 arm

What steps can reproduce the bug?

Run this code in Bun, and a runtime like Deno / Node

// Program counting fib(n)
let prev = BigInt(0);
let curr = BigInt(1);

let n = Number(process.argv.length > 2 ? process.argv[2] : null);

if(isNaN(n)) { console.log("Provide a valid number"); process.exit(0); }
let start = Date.now();
for(let i = 0; i < n; ++i){
    let tmp = prev + curr;
    prev = curr;
    curr = tmp;
}
let end = Date.now();
console.log(end - start);

Bun consistently takes ~2x as much time (Tested for n=100k, n=1mil)

What is the expected behavior?

At least the same performance as other runtimes

What do you see instead?

Slow performance

Additional information

There was an almost identical issue reported a few years ago, I was told to make a new issue because Bun has changed a lot since then

[linear]

ENG-20715

[tshmieldev]

Confirmed that this is still the case in 1.3

[jleskovar]

On my machine (Macbook M3 Pro)

$ deno perf.js 1000000
4332
$ node perf.js 1000000
4572
$ bun perf.js 1000000
7663

$ deno -v
deno 2.5.4
$ node -v
v23.11.0
$ bun -v
1.3.0