What happens when a thread is moved?
 

The steps vbulletin takes in moving a thread from one forum to another. The issue is that we have several threads that are very active. It's been recommended to close large threads to keep the load down, which is cool with me. So threads that hit 10,000 posts are locked and moved to a separate forum.

However, whenever this happens the board seizes up and is unusable for quite a while (too many connections errors). I'm curious as to all the steps that are taken to move a thread that would cause such a high load.