New Relic's RPM has became an important asset in all of my applications, plus we heavily use it for a Rails app that receives ~5 million hits per day. The best

New Relic's RPM has became an important asset in all of my applications, plus we heavily use it for a Rails app that receives ~5 million hits per day. The best way to track performance issues, and that's in production. Tip for OP: As you might already have been read on the internets, worry about scaling later, because there's a very high chance that your app will need special care and will differ from other people cases.