Wouldn't think it would be a long equation to figure out what caused it.. High Capacity and servers unable to cope? How many servers have been merged onto the Harbinger? 7-8? Didn't you just merge 2 or 3 APAC servers with it too?
The issues run much deeper than that. Rarely is the answer to performance issues "throw some stronger hardware at it". Usually it involves much more time consuming game engine optimizations etc.