In Photoshop CS6 extended, the Quick Selection Tool is not usuable. It repeatedly reports that "There is not enough RAM." That problem does not exist when I use PCS5. I use Windows 7 on a Dell Expiron with a 32bit system.
Chris, the images are 5616px x 3744px. Document Sizes are 23.4 in. x 15.6 in. with resolution of 240 px/in. They are all jpg images taken with a Canon 5D Mark II. The depth is background + background copy.