我的异步javascript quicksort执行速度不会比同步asyncjavascript快

Question

我已经用javascript编写了一个异步quicksort，以前在c ++中也做了同样的事情。但是我这里的异步快速排序不会比我的同步快速排序更快。有谁知道为什么会这样？

我尝试使用Promise.all来同时执行异步功能

如果有人能解释为什么会这样，我会很高兴的！ ：D

Array.prototype.swap = function(a, b) {
    let temp = this[a];
    this[a] = this[b];
    this[b] = temp;
}
Array.prototype.partition = function(begin, end){
    let left = begin + 1;
    let right = end - 1;
    while(true) {
        while(left < right && !(this[right] < this[begin]))--right;
        while(left < right && this[left] < this[begin]) ++left;
        if(left == right) break;
        this.swap(left, right);
    }
    if(this[begin] < this[left]) {
        return begin;
    } 
    this.swap(begin, left);
    return left;
}


Array.prototype.asyncQuickSort = async function(begin = 0, end = this.length){
    if(end - begin < 2) return this;
    let pivot = end - 1;
    this.swap(pivot, begin);
    let partitionPoint = this.partition(begin, end);
    await Promise.all([this.asyncQuickSort2(begin, partitionPoint), this.asyncQuickSort2(partitionPoint + 1, end)]);
    return this;
};

Array.prototype.asyncQuickSort2 = async function(begin, end) {
    if(end - begin < 2) return this;
    let pivot = end - 1;
    this.swap(pivot, begin);
    let partitionPoint = this.partition(begin, end);
    this.syncQuickSort(begin, partitionPoint);
    this.syncQuickSort(partitionPoint + 1, end);
};
Array.prototype.syncQuickSort = function(begin, end){
    if(begin == undefined) {
        begin = 0; end = this.length;
    }
    if(end - begin < 2) return this;
    let pivot = end - 1;
    this.swap(pivot, begin);
    let partitionPoint = this.partition(begin, end);   
    this.syncQuickSort(begin, partitionPoint);
    this.syncQuickSort(partitionPoint + 1, end);
    return this;
};

Array.prototype.generate = function(amount){
    while(this.length > 0) this.pop();
    for(let i = 0; i < amount; i++) 
        this.push(Math.floor((Math.random() * 100) + 1));
    return this;
};

Array.prototype.sorted = function(){
    for(let i = 0; i < this.length - 2; i++) {
        if(this[i] > this[i + 1]) return false;
    }
    return true;
};

Array.prototype.copy = function() {
    const arr = [];
    this.forEach(value => arr.push(value));
    return this;
};
const arr = [].generate(500000);

const syncArr = arr.copy();
const asyncArr = arr.copy();

exec();

function exec() {
    let start = new Date();
    asyncArr.asyncQuickSort().then((res) => {
        console.log('async: ', new Date() - start, 'ms is sorted: ', res.sorted());
        start = new Date();
        syncArr.syncQuickSort();
        console.log('sync: ', new Date() - start, 'ms is sorted: ', syncArr.sorted());
    });     
}