When you first start building tests in EUnit they will in general go really fast. Running your entire test suite will take a fraction of a second and it will get run a lot. However as things progress more tests will be added and each one will cause the suite to take a little longer to run. At some point You will find that instead of taking 0.2 seconds to run your suite it will take long enough to annoy you. At this point you might think that "Hey, why not run each test in its own process and have the whole thing take advantage of the fact that I have a big fast computer with lots of cores?", here is how to do it.