Sometime ago I checked this and PotM/NWN was using something like 1KB/s of my bandwidth. That is very low. 60KB per minute, 3,6MB per hour. A typical game section, player side, shouldn't eat more than 10-20MB. This was measure by my firewall 2-3 years ago. This is true because when I started playing NWN I did it with dial-up, and dial up in my city had the total bandwidth of 3,6KB/s.