As suggested, I measured the overhead at various sampling rates:

No instrumentation (otel is not initialized): CPU=2.0 cores

SAMPLING 0% (otel initialized): CPU=2.2 cores

SAMPLING 10%: CPU=2.5 cores

SAMPLING 50%: CPU=2.6 cores

SAMPLING 100%: CPU=2.9 cores

Even with 0% sampling, OpenTelemetry still adds overhead due to context propagation, span creation, and instrumentation hooks