Factory Girl is a testing framework for Ruby On Rails written by ThoughtBot.com.
This page has notes from ThoughtBot about how to do Factory Girl testing speed optimizations.
Thanks to Dan Croak, author of Factory Girl, for providing these ideas.
For example, as long as you have integration coverage
for the sign up process, you can feel confident using FactoryGirl
for a "I am signed up and confirmed as 'user@example.com'" step,
instead of a step that actually submits the sign up form again.