Hi Daniel,
this directly raises some concerns:
Do network packets that are trying to go out to the non-reachable Internet get dropped/not responded or are they properly rejected by a firewall with “ICMP admin prohibited”?
I’m asking, because I saw it too many times, that DNS or other traffic is generated by e.g. certificate validation of the OS. Then this traffic gets dropped (not responded) and therefore the program/script/powershell needs to wait for timeouts. This easily adds a couple of seconds to the total runtime - per request.
Just my 2 cent
Alex