occlusion culling

i have unity 5 pro

and i want to know how i will be able to know if the occlusion culling is enabled or disabled ?

In the scene mode there’s a camera dropdown where you can see the Occlusion Culling checkbox, already checked by default.

And for the camera’s inspector view there’s also a property Occlusion culling, that’s also already checked by default.

See the below images, i have unchecked both but it’s not desirable and slows down the rendering and even hang the game.