That's what Open Telemetry is for, honestly, specifically tracing. I'm in the process of adding tracing for all of our web handlers, http client calls, database transactions/individual queries, and asynchronous jobs. Should give us a pretty good view into the performance of the system, and allow us to monitor for things like performance regressions without any dedicated profiling needed (though we certainly could add additional profiling information through Otel down the road). Since I know you're a Haskeller (recognize your handle), the hs-opentelemetryecosystem is quite solid and has integrations with a lot of libraries in the wider ecosystem, like wai, persistent, postgresql-simple, conduit, and a bunch more. I haven't needed to write too much of our own instrumentation, aside from our job system since that's a bespoke system.