The compression is on, but there is a lot that could be done to make it faster. Dumping the CSS out of the header templates and into a CSS file would be a great move as all that would be cached for each reloaded page. That's been suggested and ignored... and if you read the list (and his reply) it's not the hosting or bandwidth that's costing all this money he's saying- it's the publicist??, the columnists (who, GroovyDruid the member??), and a lot of other stuff that's probably unnecessary. Also, the bugginess of the site and the problems come from phpNuke (pile of garbage) and not from phpBB, but that's more of an opinion than anything else.
And, k96822, what you're missing are all the posts that relate to the most recent WP scandal, quickly covered up, hence various avatars and comments...