I've always worried about phpBB having security issues and being plagued with spam. Besides, I'm not too much a fan of the design of the thing.

MyBB is very customizable (provided you have a bit of CSS knowledge) to fit your needs, and is really quick. The server, as Vanilla said, is what basically can make or break your speed. NiftyHost's things are pretty fast, I use a different host though. If you have the money to spend, I would recommend hosting some static content from your forum on a CDN (content delivery network) such as Rackspace (http://rackspace.com)'s Cloud or Media Temple (http://mediatemple.net)'s ProCDN solution. It'll seriously improve site speed. Other small factors like DNS settings influence this, too- and IntoDNS.com can help with diagnosing these issues. Google Page Speed can also give helpful suggestions on how to improve your site's speed.

Hope it helps!

i personally like phpbb

Where is the poll for this? Anyway, the best free is MyBB and the best paid is IP.Board.

<That posting too fast message is bugging me really :D>

I like MyBB, but I know (better) hot to use vBulletin.

I recommend MyBB, great manageable Admin CP, I like the speed of things, and ofcourse your server limits the forum speed, but MyBB does have an Optimization System like SMF which I recommend!

SMF if you want everything organized :P

The SMF admin panel always pissed me off.
@Matt: Try CloudFlare, it is kind of like a free CDN.
http://www.cloudflare.com

Personally I like MyBB but I have not much time to set up this software like I used to do in the past.

I tried a few weeks ago what I thought could be a better solution to suit my needs; BBpress, developed by WordPress, but it's still very plain to run a fully featured forum.

Since I can't afford XenForo, I found a similar free software called Dove Forums, but I have been busy to install it so I can only talk by the way it looks on the demo site.

And talking about demos, you can find many scripts and demos here, http://php.opensourcecms.com/scripts/sho...ory=Forums

I believe this is the best way to find exactly the forum that each one needs ;)

I have been using xenForo a lot lately, and it has grown on me. If the budget was not so tight around here I would have proposed that we use it ourselves. I mainly like the alerts system, makes it a lot easier to keep up with posts.

I like MyBB

For me, it would have to be phpBB3. I just love the whole of the software. Lots of modifications and it's very easy to edit when it comes to the themes. The theme selection for phpBB3 isn't too good, but when you make a unique you can make it look brilliant. It'd say phpBB3 is the best forum software out there, beating all the paid ones.