I know that RSpec has the --profile option, but I'm only using MiniTest/shoulda for my current project.
You can use minitest-reporters for this purpose. This gem provide multiple reporters to see output of your tests.
Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
Spec reporter shows the time which each test take to run. It shows the time on console, not as a report.