test.js

const crypto = require('crypto');

const start = Date.now();
crypto.pbkdf2( 'a', 'b', 100000, 512, 'sha512', () => {
  console.log( '1:', Date.now() - start );
});

crypto.pbkdf2( 'a', 'b', 100000, 512, 'sha512', () => {
  console.log( '2:', Date.now() - start );
});

crypto.pbkdf2( 'a', 'b', 100000, 512, 'sha512', () => {
  console.log( '3:', Date.now() - start );
});

crypto.pbkdf2( 'a', 'b', 100000, 512, 'sha512', () => {
  console.log( '4:', Date.now() - start );
});


// output
// 2: 2007
// 3: 2008
// 4: 2009
// 1: 2009