Photoshop CC causes banding to all OS

Question

I've just bought the best macbook pro available and I'm experiencing terrible graphics compared to my old late 2006 Macbook. In particular I'm noticing more banding in pictures, check this pic, I see banding in the background, I sent it to some friends that didn't notice, I dont know if their eyes are not trained or if my mac has a problem.
BUT while I was chatting with my friends about this pic the situation worsened like this
and I noticed that banding disappears when I quit Photoshop CC (But I still see some banding in the first image I linked from Flickr)

Answer 1

By the way, even for those images you've edited in 8 bits/channel and caused visible posterization, you can fairly easily repair them by doing something like this:
Select your background
Shrink the selection a good bit away from the subject (e.g., 60 pixels)
Blur the background with a large radius (e.g. 30 pixel) Gaussian Blur (so as to blend the background to use all possible adjacent levels
Then add a little monochrome noise (e.g. 0.6%) to help hide the remnant posterization.
For example...
-Noel