From my experience, in company meetings, the higher the number of participants, the longer the meeting. No matter if people has been invited just to listen and get informed of what's been going on; when somebody attends a meeting, he/she feels the urge to say something, even if it is obvious or has been said before. For one, it shows he/she has been paying attention and is up to date with the state of the business. And second, because otherwise he/she will look as nobody really important.
The same happens in forums with many members. The good thing about forums is that you can skip the posts and not read what you don't want to, but you can't shorten a meeting duration buy fast-forwarding the redundant information....
