My plugin runs 4 times slower in release than in development

Ok i have narrowed down the issue,

It is extremely surprising because the piece of code that runs slower is actually 150x slower in the release context, and doesn’t involve any api call

In order to get a fingerprint on some exported nodes, i run a hash on the bytes,
i turn the Uint8array to a string, then run the following that string: 

let ch:number;
for(let i = 0; i < len; i++) {
		ch = str.charCodeAt(i);
		h1 = Math.imul(h1 ^ ch, 2654435761);
		h2 = Math.imul(h2 ^ ch, 1597334677);
}

In my benchmark, those lines are called 3 times,  with str being of length : 3784881, 103060, 3055 (so up to a length of 4 millions basically)

in development context, those 3 calls takes 16ms
in release context, they take 2463ms (150x slower)

Is there a reason about the javascript execution context that could explain this huge difference ?

Please let me know, i really need a way to improve on this.
Cheers