How to increase data transfer speed through OpenVPN?

Question

openvpn

Basically the question is in the title. The speed drops by about half.
By the way, when I installed OpenVPN Access server on the same machine, there was no speed loss.
server.conf

port 1194
proto tcp
dev tun
ca ca.crt
cert server.crt
key server.key
dh dh2048.pem
server 10.8.0.0 255.255.255.0
ifconfig-pool-persist ipp.txt
push "redirect-gateway def1 bypass-dhcp"
push "dhcp-option DNS 8.8.8.8"
keepalive 10 120
user nobody
group nobody
persist-key
persist-tun
status openvpn-status.log
verb 3

The machine is powerful, VPN should be easy to pull. Tell me where to dig? Tried to play with mtu, tun/tap, udp/tcp, lzo - doesn't help much.

Answer 1

habrahabr.ru/post/246953

Answer 2

And what about the client side? Suddenly there the processor is loaded to capacity.

Answer 3

replace "proto tcp" with "proto udp". Not good is TCP over TCP.