I understand that it shouldn't impact response time because it does all the processing after it's been sent, but ultimately having that extra workload on your server should cause some impact, right?
Yes, extra requests your server/application has to send(to Apio) will put load on it. This is just a start so we will have to see how can we optimize this.
Maybe agent based solutions which are used by Datadog or Newrelic might be a better way than Middleware based solutions.