I'm wondering in terms of computing power for VPN and throughput on a gigabit fibre service whether the X20 or the X50 would perform better. 

I appreciate that the Wifi specs are better on the X50 - but I'm just wondering if the two extra cores make the X20 faster than the X50?

Or is the dual core X50 somehow faster?

It seems strange to me that the processor spec on the X20 seems to be better.