Testing performance on mobile devices can be pretty hard to do. There are some tools out there and one of them, Mobitest, has been <em>open sourced</em> a while ago. This tool lets you remotely run accurate tests on real devices. You can <a href="http://www.blaze.io/technical/open-sourcing-mobitest/">try it out here</a> or you can install it yourself now (which is rather complicated, like everything on mobile)

Cool timeline for rspec testing output.