It happens to us, http://worldnewstrust.com , a lot. Server loads on the butler server are very, very high. Constantly.
We contact Tech support and they tell us that they cannot find anything out of the ordinary.
I would say that there either is a site, hosted on butler, that is extremely popular or there is a hardware problem. That is a guess, as I am not able to put hands-on with the server.
We have signed up for PS, in the hopes of mitigating the problem, but have received no word on time-to-implementation. I have, yet again, sent in a ticket on the server issue, but have received no reply. I guess I am starting to get the "pest" reputation, something I have taken pains to avoid.
Living with 75-125 second page load times is starting to take the fun out of things. They are definately hurting traffic.