Comment by raphaelrk

Interesting! As a quick test on Chrome ("Version 95.0.4638.69 (Official Build) (x86_64)")

  t0 = new Date();
  a = Array(100000000).fill(0);
  console.log("time elapsed: ", new Date() - t0); // 22912
  a[100000] = 1;
  a[10000000] = 1;
  a.forEach(e => e == 1 && console.log(e));
  console.log("time elapsed: ", new Date() - t0); // 28371
  
  t1 = new Date();
  a = Array(100000000);
  a[100000] = 1;
  a[10000000] = 1;
  a.forEach(e => e == 1 && console.log(e));
  console.log("time elapsed: ", new Date() - t1); // 2787

Upon doing a couple not-so-scientific runs of this, it looks like the latter isn't really faster than the former.