I'm using a VPN to download things via transmission. My question isnt related to speed, as i'm downloading at 1.1MB/s!

My question relates to how Transmission utilises network interfaces. I use iStat Menus to monitor network usage, and as far as I can see, most of the data is not being downloaded through the VPN, but instead through the local internet connection, even though I have set the VPN to route all traffic through it.
The odd thing is, that for all other network traffic, data seems to pass through the VPN, Transmission seems to be the exception. Just to clarify, the network activity here is just transmission traffic, and no other local network traffic...
Here is a pic:

So my question is more about getting a better understanding about how Transmission utilises network connections. Will it follow system settings and use the VPN or is iStat menus wrong?
I'd be interested to see if anybody else has had a similar experience!