Performance/framerate issue

I was playing with a scene that had 1.3M tris, and getting terribly low framerates. I tried to see how things would be by eliminating things, and I eventually came upon a scene that was basically just the skybox. Still, my framerate is under 30fps. Any idea what might be causing the issue?

(Note: I don't have a dedicated GPU, and that could be an issue. But still, I have got > 60fps before and this is just a plain scene with 48 tris, so there's no reason for this to have such low framerate).