I did some testing a while back that may help you with some reference numbers on throughput. These are my speeds using the OpenVPN Client on two different ASUS routers. Both routers running Asuswrt-Merlin 380.64 firmware. Using the VPN client to connect through PIA VPN servers.
AC3100 (1.4 Ghz dual core)
CTF enabled
DL: 61 Mbps with core 1 at 25%, core 2 at 75%
UL: 84 Mbps with core 1 at 35%, core 2 at 100%
AC68U (1.0 Ghz dual core)
CTF enabled
DL: 44 Mbps with core 1 at 30%, core 2 at 80%
UL: 58 Mbps with core 1 at 40%, core 2 at 100%
https://www.snbforums.com/threads/ve...3/#post-311883
Sto ne mora znaciti da ces imati ti iste rezultate, jer sigurno su razlicite postavke openvpna. Al ovo gore bi ti trebao biti ok forum za naci iskustva ljudi.