Making the obvious code fast (2016)(jackmott.github.io)

    [dup *] map sum

    sum == 0 swap [+] step

    0 swap [dup * +] step

    for (int i = 0; i < x.length; i++) {
        z[i] = x[i] * y[i];
    }

    <script>
    let arr = new Float64Array(32000000);
    let sum = new Float64Array(1);
    sum[0] = 0;
    let l = arr.length, i, el;
    // Initialize with radom values
    for (i=0; i<l; i++) arr[i] = Math.random();

    // Sum
    let st = performance.now();
    for (i=0; i<l; i++) sum[0] += arr[i] * arr[i];
    let en = performance.now();
    console.log(en - st, sum[0]);
    </script>