Closing day talk I gave at RubyC in Kiev: http://rubyc.eu/
Further read:
- The Flame Graph: http://queue.acm.org/detail.cfm?id=2927301
- flamegraph gem: https://github.com/SamSaffron/flamegraph
- rack-mini-profiler: https://github.com/MiniProfiler/rack-mini-profiler
- ruby-prof-flamegraph: https://github.com/oozou/ruby-prof-flamegraph