New Relic is a performance management system, developed by New Relic, Inc (http://www.newrelic.com). New Relic provides you with deep information about the performance of your web application as it runs in production. The New Relic Ruby Agent is dual-purposed as a either a Gem or plugin, hosted on http://github.com/newrelic/rpm/
Gemfile gem 'newrelic_rpm', '~> 3.4.1'
install gem install newrelic_rpm -v 3.4.1