[orban]

I think the difference between big boards and other boards is that you run into problems that smaller boards or with less visitors never will have.

Examples:
-Search
-Caching (both code and content)
-Server Hardware
-Apache/Lighttpd
-Table Locking

As a board with 30 users online you will never have these problems even with 1000 million posts. Our problems basically started with ~ more than one million posts and more than 1000-1500 online (everything else makes our server run at <2 load). And you can do a hell of a lot of optimizations if you put the time in it.

Problems like "I have 50 queries on my forum home and it runs very slow on my shared host with 512mb ram" or obviously misconfigurations of apache/mysql/etc should be in a general optimization forum like the one on vbulletin.com to be honest. But I don't really care, if I see something I can help out I'll post my cents.