I think the idea here is to separate the log call site in application code from the log processing/persistence? So, the nanosecond values quoted are the impact

I think the idea here is to separate the log call site in application code from the log processing/persistence? So, the nanosecond values quoted are the impact exposed to your application code, but some other process takes over the bulk of the work of the logging. So as long as the offloaded process can keep up with the average log rate, it'll be fine - but also as a bonus the application does not see increased latency due to logging.