Very poor performances with TypedArrays

[Amoki]

Description

I'm working on creating a LWC with our 3D building viewer.
The 3D engine uses Float32Array to build GPU buffers.
When using Lightning Web Security, it is very slow. Operations usually done in ~0.5 second can take up to 50 seconds.
Digging in the debugger, I found assignation is very slow.

Steps to Reproduce

Go to https://developer.salesforce.com/docs/component-library/tools/lws-console

Copy-paste following code:

const size = 10_000_000;
const array = new Float32Array(size);

console.time("OperationTime");

for (let i = 0; i < size; i++) {
    array[i]++; // Any assignation is slow
}

console.timeEnd("OperationTime");

Open the console, toggle LWS: Enabled/LWS: Disabled and click on Evaluate

If needed, I can provide a more complex example.

Expected Results

Execution time similar with LWS (or at least not 50x slower)

Actual Results

Firefox: 7320 ms with LWS, 170 ms without
Chrome : 2902 ms with LWS, 50 ms without

Browsers Affected

All

Version

Tested with LWC 5.0.2
I don't know which version lws-console uses.