random.js

const crypto = require('crypto');
const [_bin, _script, lenStr, algo] = process.argv;

const array = [];
const length = Number(lenStr);
if (algo === 'crypto-random-fill') { // ~23100ms for length-10000000 array
  const bytes = Buffer.alloc(6);
  const coeffs = [40, 32, 24, 16, 8].map(a => Math.pow(2, a));
  for (let i = 0; i < length; i++) {
    crypto.randomFillSync(bytes);
    array.push(String(
      bytes[0] * coeffs[0] +
      bytes[1] * coeffs[1] +
      bytes[2] * coeffs[2] +
      bytes[3] * coeffs[3] +
      bytes[4] * coeffs[4] +
      bytes[5]));
  }
} else if (algo === 'crypto-random-bytes') { // ~27700ms for length-10000000 array
  const coeffs = [40, 32, 24, 16, 8].map(a => Math.pow(2, a));
  for (let i = 0; i < length; i++) {
    const bytes = crypto.randomBytes(6);
    array.push(String(
      bytes[0] * coeffs[0] +
      bytes[1] * coeffs[1] +
      bytes[2] * coeffs[2] +
      bytes[3] * coeffs[3] +
      bytes[4] * coeffs[4] +
      bytes[5]));
  }
} else if (algo === 'math-random-max-safe-floor') { // ~3800ms for length-10000000 array (6300ms without Math.floor)
  for (let i = 0; i < length; i++) {
    array.push(String(Math.floor(Math.random() * Number.MAX_SAFE_INTEGER)));
  }
} else if (algo === 'math-random-1e64') { // ~4200ms for length-10000000 array
  for (let i = 0; i < length; i++) {
    array.push(String(Math.floor(Math.random() * 18446744073709550000)));
  }
}

Note: I screwed up a little bit (coeffs pre-map should have multiples of 8 instead)... fixing