Why does Google stick to very out-dated USNET style groups? No one else uses those anymore, as they have long been replaced by Forums. Now there is everything from paid vBulliten to PHPBB. Why would anyone use Google Groups?

A great move for google would be to buy MyBB. Their support groups are all 90% spam, and impossible to use. Having more recognizable staff assistance couldn't hurt either.

They are fast, secure, easy to read & react quickly. I'm sure your PHPbb isn't so reliable.

no?

I personally find MyBB the best. Have a look: http://community.mybboard.net/

(no, I don't work for them)

Sure, it is the best if you have only 10 active members, if you like to customize the theme and often use the calendar module.
If you have to handle about 70 messages / minute, I doubt your MySQL database will support that.

Public groups are very difficult to read because of all the spam. Private groups are a great way to have a place for a group in a meaningful and cohesive fashion.

It isn't ideal, but it has threaded conversations like Gmail and it has amazing search. Good enough for me. And it's free.

TOMHTML: I don't see any Google Group getting 70 messages / minute.

Anyway, that would all depend on the server, not really the software. And there are some pretty big forums.

deathrowdoggie: Many forums are also free. and both public and private ones have less spam.

The Coder: I often go on a private group for my class, the average is 3 posts per minute during the day. It is frequent that I leave the group 10 minutes, when I'm back there are no less than 100/150 new messages.
The only bug comes from.... Gmail, when I check threads by mail. It froze because of the number of messages.

Have a look at http://rankings.big-boards.com/

There are some pretty big ones. As I said, it all depends on the server.

And they don't require email.

Some math shows that http://www.gaiaonline.com/forum has ~375 posts per minute

So it needs a big infrastructure!

Finally, the chose of a forum depends on... the users. 10 or 10'000? By mail or by web interface? Loving customized themes or loving simplicity?
That's why we don't have the same point of view.