Yes Elder, I have only noticed it in PvP.
Not sure exactly how they have the servers set up to route data, and how it differs via different PvE/PvP regions. But it does indeed, change.
I've also just submitted the issue, along with my dxdiag to support. Since they are aware of this problem, but that post was from 2007.
Since the regions seem interconnected is there any way to make sure my connection only connects to US servers only?