The forum now has over a quarter of a million users. Several hundreds are connected at one time. These people contribute nothing to the community but being parasites that make the forum slower. Quite often they are so busy that the search function is no longer available to genuine users. One of the causes is that the main pages gets ever longer because of all those phoney birthdays (ranging from 26-39 years). You could block birhdays and their display:
ACP->main page->load settings->enable birthday listing->set to NO.
ACP->main page->board features->allow birthdays->set to NO.
It is a well known fact that on many fora the Private Messaging function is abused by people who see it as a convenient hidden chat function. I can't see if this is happening substantially on this forum, but you might consider switching off the PM feature
Since 29-12-2016 I am no longer a moderator for this forum