On the moment I have a 150 Mb/s - 20 Mb/s ISP connection and my max speed over VPN is 7Mbps
So I am astonished that it is possible to have 140Mbps; that's 20 times more!
I thought it was not possible and that the air vpn servers were the bottleneck.
But now I am not so sure anymore about that...
I was hitting around similar with my Asus tomato router, I ignored a few comments about people saying you wont get faster but sadly they were all right.
Eventually routers are just too slow. Even the latest netgear router with dual core 1ghz cpu wont do much more then around 20meg under an VPN with AES encryption.
So its time to build a pfsense. Many pfsense guys I noticed have just used an old pc or got a cheap pc of ebay and converted it into an router and I prefer this. However trying to get a low powered and low wattage AES compatible CPU and one with 2-4 ethernet ports which are all compatible with pfsense is slightly tricky. But check Knickers hardware I feel he has got it bang on.
I would have loved to use one of those tiny pcs that consume 15-20watts but I don't feel that is happening since they lack AES or ethernet ports.
Shame Shutlle DS61 V1.1 did not upgrade to a haswell system, some core i3s @ 55watts and some cpus with 35watts even about....