Yes, I've been quite unfair to Ubuntu forums. While I'd still prefer if they (= not Canonical; Ubuntu forums is just affiliated) would enable some searching for non-registered users, I have to accept that they only have limited hardware resources. And of course I'd like to see them using Opensource Software for their forum.

When they enabled searching apparently they were flooded with requests. This goes so far that there are even rumors about a DDoS launched against their search functionality (the mails I received from UbuntuForum admins did not contain this claim).

UbuntuForums definitely is a huge forum. The front page says "Threads: 243,764, Posts: 1,440,895, Members: 160,228, Active Members: 121,548".

Well, 1.4 million posts definitely is a load of data to search in. I don't know if phpBB and similar opensource forums can handle these numbers (I have very little trust in any PHP solution, as you might now, and I dislike phpBB a lot). However I believe they're more likely to receive support by their developers for modifying the forum to handle such numbers. If they actually perform worse (which I don't know. Has anyone resources on the performance of different forum solutions with huge user and post numbers?)

Maybe they're just hidding limitations of vBulletin now, too. I could imagine they need to replace the built-in search functionality (which I guess is MySQL-based) with e.g. a lucene based search. This should also allow better distribution of the system onto multiple computers.

Anyway, I didn't mean to flame the Ubuntu community that much. It's just that the forum lost the one essential function for me this way - searching if the answer to my question is somewhere in there. (And yes, I know that registering isn't hard, and that they don't even verify the email address.)