you have the same cpu and video card as me, only difference is i have 8gb of memory instead of 4... i still only get ~15-20fps in busy areas of dalaran but there's not a ton you can do to get better than that right now

also your resolution is higher than mine, i'm at 1680x1050 on my main, 800x600 x 4 clones
and what do your video settings look like? i'm all maxed out on my main, everything but spell detail turned down on the clones