Very poor OpenVPN performance

  • Hey guys I'm paying for a public VPN service, so I don't control the server side only the client side.

    The problem I'm having is when I use the OpenVPN Client on my desktop or laptop computers the speed is excellent around 200Mb/s consistently.

    But when I use the OpenVPN Client in PFSense the speed is very low, 5-10Mb/s and if it gets any higher (30-40Mb/s) I get huge amounts of packet loss and very high latency being reported in the PFSense Status Page.

    Here are two speed tests to illustrate the problem:

    I did these tests within the same minute late at night when the network should have no congestion so you can really see the problem. Both my Windows/Mac OpenVPN Client and the PFSense Client are setup the same except for one difference, the Windows one uses a TAP interface and the PFSense is using a TUN interface. Apart from that they're both using UDP, same port number, same level of compression, same server that they connect to and of course through the same modem and the same ISP on my side. I have tried using OpenVPN over TCP instead and the results are identical.

    Does anyone have any thoughts about what this could be? I'm also going to list my router specs although I think it's beefy enough to handle much higher speeds than this.

    The router is running an Intel Haswell G3220 Pentium chip (3GHz Dual Core with 3MB Cache). 16GB of DDR3 Memory, on-board Intel NIC on the motherboard (WAN) and another Intel NIC in one of the PCIe slots (LAN). The system I'm using for both of those speed tests also has Intel NIC's from an X79 motherboard. It is equpped with a 3930K and 32GB of DDR3.

    When doing the speed test on PFSense the CPU load is only around 10-15% and the RAM usage is like 2GB out of 16GB. So I'm really not thinking it's the hardware but some kind of configuration issue or some setting I'm overlooking.

    By the way I'm still using PFSense 2.2.6 - I've not yet upgraded to the latest version but I do plan to soon.


  • I have a very similar issue on 2.3.1 p1. I will open another thread for that as we are dealing with different pfSense versions.

  • Did you manage to figure out the reason behind the performance problems? If so, could you please share what you've done?

  • same issue facing in latest version i think this is the bug which should be reported to the developers ASAP.

  • Are you using IDP in PFsense if it is free version then it may be the reason.

  • That chip doesn't support AES-NI, that's one of the big issues.

  • @0x10C

    in the OpenVPN Client you could try to increase the TCP/UDP socket send and receive buffers size, adding at bottom of the "Custom options" these two lines:

    sndbuf 524288;
    rcvbuf 524288

    About the OpenVPN capability of the CPU you could run the simple OpenVPN benchmark formula referenced here: in the Reply #9 message

    If I execute the command on my router with a Celeron N3150 I get
    27.41 real        25.62 user        1.77 sys

    (3200 / 27.41) = 117 Mbps OpenVPN performance (estimate)

    This value perfectly fits to the result of the speed test

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