Strange memory behavior on the agenda

Question

I just started using agenda in a node js application and I find strange memory behavior. The amount of memory is increased by 200 KB after each job. Here is a simple example demonstrating the same behavior.

var Agenda = require('agenda');
var agenda = new Agenda({db: { address: 'mongodb://localhost:27017/my-test-db'}});
agenda.define('say hi', function(job, done) {
  console.log('Hi!!!!')
  done();
});
agenda.every('10 seconds', 'say hi');
agenda.start();

Any idea why this is happening?