Instead of using the built-in `Array.forEach`, consider using [async](https://github.com/caolan/async)'s [queue](https://github.com/caolan/async#queue), which will only process `n` number of things simultaneously. Good to make sure you don't overload the DB!

You can also use the [waterfall](https://github.com/caolan/async#waterfall) to process steps of the migration in sequence.