perhaps a driver problem? that computer should be screaming fast for wow.

what driver version are you running with?
1 - right-click desktop , click on "nvidia control panel" from the menu
2 - in the nvidia control panel, at the top of the control panel, click "help" and select "system information"
3 - in nvidia system information screen, click "about" button at the bottom-right corner
4 - post the version number

also make sure the computer components are not overheating as that will drop your FPS as well.

Check the settings of wow, multiboxing program, computer settings, and make sure video card settings are default and make sure you are not using any AA or other video enhancements.

make sure SSD is not full, as it will decrease performance of it and run the "intel SSD toolbox" on it when not in use every week.