I am still looking for a bulletin board/mailinglist integration software

The "horizontal-split" mode is rather nice.

Meanwhile, I think it's fast because unlike most other forum software, it doesn't pollute the pages with animated GIFs or - as is also the case with most Web sites these days - thousands of lines of scripts to decorate all the parts of the page after loading, play with the layout, and reinvent things like hyperlinks and the back button because the experience is not "desktop-enough" for the assumed audience otherwise.