the problem isnt you, or at least i doubt it is as many of us run accross these lag issues as well. i suggest you look here for part of your answer:
http://forums.worldofwarcraft.com/threa ... ost6635412
i wouldnt expect this to be fixed tomorrow, but they are aware of the issue. they have expressed upgrades are near so they have the approval for new hardware in their budget. working in the IT world, i would expect things to get better in the coming WEEKS at the very earliest.
they know we are suffering and its not just BL.