How do you know what parts of the workflow need improvement? Measure it. With New Relic in place, we have graphs of our API performance and can directly see if a server or zone is causing trouble, and the impact of our changes. There’s no comparison between a real-time performance graph and “Strange, the site seems slow, I should tail the logs”.
Free Heroku add-on. Not particularly useful for us. Rails profilers tend to do a better job at the app level. And I can never really figure out what’s going on with Heroku by looking at New Relic. I don’t know if we’re just not using New Relic correctly or if it really does just suck for our use case. But I guess some insight is better than none.
We monitor and troubleshoot our app's performance using New Relic, which gives us a great view into each type of request that hits our servers. It also gives us a nice weekly summary of error rates and response times so that we know how well we've done in the past week.