Question

• Is vm.runInNewContext considered black magic like eval?
• Is there a
  significant performance difference between require and reading a
  file and using vm to run it or is the the same under the hood (if
  you implemented caching etc and just wanted to add some variables to
  the context)

Answer 1

runInNewContext is not meant to be used as a replacement of require or eval, but instead as a way to create a sandbox environment where you can safely run other scripts.

Disadvantages are that it’s slow (creation takes ~10 ms.) and takes up a couple megabytes. So no, don’t use it as a require replacement.