There may be some truth to that for phpBB "out of the box" - but there are numerous MODs available free which make it quite powerful. I'd say about half the MODs on my forums are behind the scenes, many of them enahncements to the ACP. But I'm interested in the speed / server load issue -- my impression on most vBulletion forums (DP is an exception) is that it is slower than a good phpBB setup. If the new vBulletin has an advantage in that area, that might be the determining factor for me.
vBulletin has always been faster and require less server resources than phpBB for me. I never tried vBulletin 2.x, but 3.x most definitely is faster and consumes less resources than phpBB.
Shawn, the puzzle for me is that this forum has always been speedy from the time I first joined. However, that hasn't been my experience with other vB forums, which I've generally found to be slow as molasses in January (Canada version). It's one of the main reasons I have stayed away from vB in the past. When I first came here, I assumed you had tweaked vB in some way to overcome that aspect of the software...
Nope, I haven't done any backend changes. To be honest, it's probably *why* it's faster. I haven't added lots of what I consider crap (ads, CMS, etc.). A good way to test it for you would be to go to vBulletin's forum since it's obviously 100% stock.