consistently low fps

I recently started playing World of Warcraft again, and have been using the same laptop I used when I used to play back in 2009. Back then I just got the laptop and was getting around the 30 - 60 fps mark even when in Bg's/Raids. I've recently started playing again 3 years on, and am now getting anywhere from between 3 - 14 fps, even with the lowest graphic settings (view distance at it's lowest etc). Back when I used to play I had the graphics settings on normal, and it's still saying the reccomended graphics settings for my laptop should be normal.

Now, is there any way that I can improve my FPS, without forking out any money? I've used up half C: drive, would this affect it at all? Could it be the new content that's slowing the frame rate down? Has anyone got any tips on how to make it higher?