I started seeing horrible Rails app initialization time when testing my rails application, but this slowness can be mitigated if you use nice assisting tools like spork and guard. Also ruby 1.9 >= through <1.9.3 does not load requirements in a efficient manner. There is a patch for 1.9.2 that improves requirement loading that helps. There are many ways to improve Rail's test performance. If you spend the time to tune your tests and test environment, Rails test performance should be good.