OpenVPN is among the most popular VPN servers today.
Unfortunately, it seems to come with defaults that considerably lower maximum throughput.
Here are the tweaks I employ to increase my speed by a factor of 15-30x.
# usually resides in /etc/openvpn sndbuf0 rcvbuf0 proto udp # instead of tcp
# in your ovpn file (or specify as command-line arguments) tun-mtu 8192 fragment 0 mssfix 0 sndbuf 0 rcvbuf 0 cipher camellia-128-cbc proto udp # instead of tcp
Here are the numbers from speedtest.net, before I employed the tweaks:
ping 126ms dl 0.5mbps ul 0.5mbps
And this is afterwards:
ping 74ms dl 15mbps ul 1mbps
Besides these numbers, I can regularly see the speed improvements in my torrent client.