I have recently, speed which I would quote "catastrophic" when I use torrent clients.
OS : Windows 10
AirVPN : Eddie last version
Torrent Clients tested : qBitorrent, Transmission or Deluge.
Speed test : 50Mbps download/upload on VPN
Without AirVPN, the torrent download speed can reach 60/80 Mbps.
With AirVPN, the torrent download speed can reach 100/200 Kbps.
The port is set on torrent client and configured on AIRVPN port forwarding.
Checked that this port is considered open.