10fps is whats killing you. Turn everything down.
-Make sure Multisampling is set to 24x 24x 1x
-Turn off Shadows
What Video card do you have? How much RAM does your pc have?
Also, update your video drivers (Nvidia 174.74 or so caused "Windowed Mode" to run at 60% capacity). This sometimes fixes problems as WoW upgrades things but the old drivers don't work as advertised. Blizzard then complains, and the video card company jumps and asks "How high?" mid air.
WoW is driving 20% of their mid-grade card sales. They listen :P