SOURCE

const arr = [];
const obj = {};

for(let i = 0; i < 100000; i++) {
  arr.push({ value: i });
  obj[`${i}`] = i;
}

const start = new Date().getTime();
let end1;
arr.forEach(e => {
  if (e.value === 80000) {
    end1 = new Date().getTime();
    console.log(end1-start);
  }
})

let temp = obj['80000'];
const end2 = new Date().getTime();
console.log(end2-start);