Hello. I don't know if it will help you, but It definately helped me.
I run win7, so what I did was that whenever I opened the client/game I clicked ctrl+shift+esc and then found dbog.exe under the second tab and set its "Priority" to at least High.
Most of the mmo games are cpu dependant and even if you have a 3000$ gpu it won't help you, when the cpu has a hard time proccessing stuff all-together. So increasing it's priority will definately skip some other lower priority stuff and work on dbo more.
Tell me how it went