FireBrick IPsec Throughput

On a FB 2700, throughput should be around 10Mb/s.

Here is a speedtest from a Road Warrior on a good internet connection connected to a FB2700 on a single 60Mb/s down and 20Mb/s up FTTC:

Speedtest over a FB2700 IPsec tunnel

Download over a FB2700 IPsec tunnel

A FB6000 can do nearer 50Mb/s, whilst newer generation of FireBrick hardware should be even better.