Производительность сети Python Stackless, ухудшающаяся со временем?

let items = [
    {'id': '1', 'size': 10},
    {'id': '2', 'size': 4},
    {'id': '3', 'size': 6},
    {'id': '4', 'size': 21},
    {'id': '5', 'size': 2},
    {'id': '6', 'size': 1},
    {'id': '7', 'size': 6},
    {'id': '8', 'size': 7},
    {'id': '9', 'size': 8},
    {'id': '1', 'size': 13}
];
//sort the array by size in reverse order
items.sort((a, b)=> b.size - a.size);
//array of sums
let sums = [0,0,0];
//final array of 3 arrays
let arrays = [[],[],[]];
for (let item of items) {
    //get index of the smallest sum
    let index =  sums.indexOf(Math.min.apply(null,sums));
    //add current item size to corresponding sum
    sums[index] += item.size;
    //add item to corresponding array
    arrays[index].push(item);
}
console.log(arrays);
console.log(sums);