- Previously ...
XHprof before and after deploying a change, with aggregation and comparison.
I was impressed by the session in Amsterdam where the tool to profile effects of a patch (profiling drupal before and after it was applied) was presented.
I thought i could use it to profile changes to a site we were then trying to optimize. It showed up that tool was too much intertwined with the patching process, so we came with our own way, based on XHprof.