Reading the Fire: Flamegraphs and the Hunt for Node.js Bottlenecks

You can’t fix what you can’t see—and when it comes to performance issues in Node.js, flamegraphs are one of the most powerful tools you have. But what are they, really? And how do you actually use them?

In this episode, we break down everything you need to know about flamegraphs—from the theory behind them to their implementation in Node.js. Whether you’re chasing event loop delays, CPU hotspots, or blocking I/O, flamegraphs reveal what your app is really doing under the hood.

We’ll cover:

✅ What flamegraphs are and how they visualize stack traces over time

✅ How they’re implemented in Node.js (using V8 and async hooks under the hood)

✅ How to generate and capture them in dev and production

✅ How to read them: interpreting stack height, width, and call depth

✅ Real examples of uncovering performance bottlenecks

✅ How we’ve built automated flamegraph capture into

Platformatic WattIf you’ve ever struggled with unexplained latency, inconsistent P99s, or just want to understand your Node.js app at a deeper level—this episode is your crash course in seeing the invisible.