OpenVPN slow

[hypemedia]

I have a OpenVpn Server config that is very slow I get transfers of 800Kb/s via the VPN while without the VPN the speed is around 30 Mb/s

The VM is running on KVM.
AES-256-CBC
SHA256

The CPU is an Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz (2 cores).

Any ideas on what it can be. I have tried also lower security encryption and different configurations but the speed is the same.

Is there anything that I can do to improve this?

The CPU is at 100%.

[Gauss23]

The CPU is at 100%? Only when OpenVPN is enabled or always?

Your CPU should be capable of much more.

Maybe the throughput bottleneck is the other side of the tunnel?

I optimized my throughput by trying different values for the custom option: tun-mtu 1500
Tjis is obviously only for a tun device.

Don't know if it's still needed but smb transfer speed were much higher with this option than without.

In any case your CPU should not be at 100%.

[hypemedia]

The problem was an old version of KVM after the upgrade the speed went normal.