It's running on 3 dedicated servers. 2 webservers loadbalanced and 1 database server. The webservers are using eaccelerator.
Gzip was disabled and I used mod_deflate to zip all non-img static files. We just upgraded to ipb3 from ipb2, so we're still testing things out.
As it seems that ipb3 is causing twice as much load.
Also, for search we used xapian and sphinx. The database is using innodb for the large and fast-update tables like posts, members and session.
kmf got a reaction from Matti in How do I scale IPB to handle 25000 simultaneous users?
