When you change perspective from 'front view' to 'back view' the world you would have to see, doesn't load untill you move your mouse.

In the screenshots you see, when i switch from 1st person view to my front view, the world doesn't load behind me, untill i move my mouse.

Then, when the world is loaded, i switch back to 1st person view, and again, the world i need to see doesn't load untill i move my mouse.