[NathanKP]

Flame graph is only needed if you are having a lot of trouble pinning down the exact call that is taking a long time. In most cases I've found traces to be all I needed. For example if I see that this span of execution took longer than expected and I read through that code and see a bunch of JSON serialization its pretty obvious.

To be honest that comes with a lot of Node.js experience though. You probably need flame graphs to start out with, but eventually I find New Relic traces to be all I need, as I already have a sense for the relative CPU weight of the various calls inside a trace span.