const crypto = require('crypto');

const pass = 'pass';
const salt = 'salt';
const start = Date.now();

crypto.pbkdf2(pass, salt, 1000000, 128, 'sha512', () => {
  console.log('1:', Date.now() - start);
});

crypto.pbkdf2(pass, salt, 1000000, 128, 'sha512', () => {
  console.log('2:', Date.now() - start);
});

crypto.pbkdf2(pass, salt, 1000000, 128, 'sha512', () => {
  console.log('3:', Date.now() - start);
});

crypto.pbkdf2(pass, salt, 1000000, 128, 'sha512', () => {
  console.log('4:', Date.now() - start);
});