Datadog RUM tuning for noisy apps
Default Datadog RUM is too noisy and too expensive. Three setting changes cut my session ingest by 70% and made the dashboards actually useful.
Datadog RUM out of the box ingests every session and tracks every interaction. That's fine until you ship to production and the bill arrives. Three changes turn it from expensive noise into a useful tool.
First: sample sessions, not actions. `sessionSampleRate: 30` keeps a third of all sessions, but with full action fidelity inside those sessions. That's better than 100% sessions with action sampling — it preserves narrative within a user journey.
Second: drop noisy custom events. The default tracking captures route changes, fetch calls, and clicks. If your app has a chatty client (heartbeat polls, telemetry pings), explicitly drop those in the `beforeSend` hook. They're 90% of your event volume and 0% of your debugging value.
Third: set a hard quota on Long Task tracking. Long Tasks are useful but verbose, and on a Tailwind v4 app under hot module reload they fire constantly in dev. Disable in dev, sample in production.