Multi-threading?

I tried optimizing the function, removing functions call seem to help quite a bit, and prevent stack overflows just a bit since it is easy to get one.

qsort: 165526.5649749999865889 (0.398799999995389953255)

swap and qsort_partition not needed anymore:

// Quick sort
Array.prototype.qsort = function (left, right) {
  var pivot, newPivot, pivotVal, tmp;

  if (left === undefined) {
    left = 0;
    right = this.length - 1;
  }

  if (left < right) {
    pivot = left + Math.ceil((right - left) / 2);

    // Partition
    pivotVal = this[pivot];
    newPivot = left;
    this[pivot] = this[right]; this[right] = pivotVal;
    for (var i = left; i < right; i++) {
      if (this[i] < pivotVal) {
        tmp = this[i]; this[newPivot++] = i; this[i] = tmp;
      }
    }

    this.qsort(left, newPivot - 1);
    this.qsort(newPivot + 1, right);
  }
};
Uint16Array.prototype.qsort = Array.prototype.qsort;