I setup an OpenVPN tunnel between two hosts with 50Mbit/s connection. If I test the speed of the endpoints, it's give the 50Mbit speed exactly. But when I do the same over OpenVPN connection, it's limited to 20MBit/s.
Meanwhile the VPN servers (both are rackable servers with high performance) has no significant performance issue. Under 10% CPU usage always.
What would be that setting on OpenVPN what can cause that ?