const c = 1000000;

var v = 10;
let l = 10;

var vo = {i: 10};
let lo = {i: 10};

console.time('var');
for(let i = 0; i < c; (v = i++));
console.timeEnd('var');

console.time('let');
for(let i = 0; i < c; (l = i++));
console.timeEnd('let');

console.time('var object');
for(let i = 0; i < c; (vo.i = i++));
console.timeEnd('var object');

console.time('let object');
for(let i = 0; i < c; (lo.i = i++));
console.timeEnd('let object');