Chrome 分析器中的“未优化”警告是什么意思

Javascript
function calculateSum() {
  let sum = 0;
  for (let i = 1; i <= 1000000; i++) {</p>    sum += i;
  }
  return sum;
}
function displaySum() {
  const sum = calculateSum();
  console.log(sum);
}
displaySum();

Javascript
function calculateSum() {
  const sum = (1 + 1000000) * 1000000 / 2;
  return sum;
}
function displaySum() {
  const sum = calculateSum();
  console.log(sum);
}
displaySum();