[cheat-master30]

It is 99% likely the shoutbox causing it. I use the exactly same kind of shoutbox, have the exact same web stats and checked, and it's usually the shoutbox which both uses most bandwidth and has most page loads/hits. Of course, there is a problem, in that Inferno vB Shout, while supposedly using less bandwidth, uses a ton of CPU instead, and shoutboxes in general are prone to high bandwidth consumption, so if you get too screwed, disable the thing.