Benchmarking Rails unit tests?

I'm having trouble for some reason finding information about the
scripts in script/performance (benchmarker, profiler, request).

I know how to use the Ruby Benchmark class to do isolated
measurements, but does Rails have a facility for running all of my
tests (unit, or functional, or all), and letting me know what are the
(say) top 10 methods that are taking the longest?

I don't want to optimize everything. I'm figuring there are just a
few bottlenecks that are slowing everything down.

Any suggestions?