as far as I can tell, it only executes the trace when asked. It's not an APM like newrelic. Most likely the trace meaningfully slows down the individual request.

When I was at ScoutAPM, we built a version of this that was stochastic instead of 100% predictable. We sampled the call stack every 10-50ms. Much lower overhead, and it caught the slower methods, which is quite helpful on its own, especially since slow behavior often isn't uniform, it happens on only a small handful of your biggest customers. But it certainly missed many fast executed methods.

Different approaches for sure, solve different issues.