Slow VPN speed on single connection

[gevero 3]

I am running the following system:

 

• Raspberry pi 2 with ArchLinux Arm Kernel 3.18
• Provider Down/Up Speeds: 70/10 Mbit
• I can maxout Up and Down speed without VPN
• If I use my laptop (Manjaro linux) i can maxout the connection even behind the VPN, so this is not provider traffic shaping

When using the VPN the following happens

 

• I try to to download anything using a single connection (for instance using "aria2c -x 1 -o /dev/null download_url") my top speed is going to be ~150KB/s with negligible cpu load.
• I try to the same thing using multiple connection (for instance using "aria2c -x 10 -o /dev/null download_url") my top speed is going to be ~600KB/s, and in both case cpu load from openvpn is about 30%, so this is not a cpu issue.
• If try to download a single torrent (extremely well seeded) I reach even better speeds (~1.5MB/s), with about 50% cpu load from the openvpn process.
• The only way to maxout the cpu and the download speed is to download several well seeded torrents at once (so a lot of connections I believe), getting 3MB/s (the expected cpu limit) with 100% cpu load.

I can't say what is going on, but apparently it looks like that a "single" connection is going slow (maybe for some faulty network configuration?) and the only way to saturate the speed is to use several connections at once.

 

Is anyone able to give any help?

 

Best

[OpenSourcerer 1359]

Yes. Execute OpenVPN somewhere else.

I would find this extremely unsatisfying. With 3 MB/s you are at roughly 24 MBit/s, which is roughly one third of the downlink capacity your ISP offers you.

[gevero 3]

Hi

 

To me 3MB/s are ok, considering that the Pi2, is cheap, consumes a small amount of power, and is running 24/7.