WAN connection utilizing only 1/3 of SDSL bandwith

[GSED]

First of all I'd like to say thanks to everyone who's involved in the development of pfSense!

According to the RDD graphs the maximum for in and out is ~2 Mbit/s whereas the bandwith of our SDSL line is 6 Mbit/s. Directly connected to the ISP's router or using a Linksys router we can get close to this bandwith, but not using pfSense.

Any ideas where to look for the obstacle?

2.0-RC1 (amd64) built Feb 26 running as a virtual machine on an ESXi host on a DELL R710 with BCM5709 and Intel 82576.