Photoshop CS6 seems to run faster for me that CS5, which was not the case with the early versions of Lightroom 3, and Lightroom 4 is still acting somewhat laggy. ACR 7 works very smoothly for me with no lag to the controls. I don't know why this should be the case when Lightroom 4 is based upon ACR 7. I really like the updated interface in PS CS6 as well. Really haven't begun to explore the new features yet, except for content aware patch, which seems pretty nice.
Also, if you do video, or plan to, the ability to run video through CS6 and use it to correct lens distortion, vignetting and CA seems awesome.