Working with a large file in PS CC (a letter-sized 600 dpi photo image from my files) on a Macbook Pro mid-2012 16GB RAM w/ NVIDIA GeForce GT 650M 1024 MB, running 10.8.4.
PS CC (14.0 x64) froze as I attempted a "skew" operation on the primary layer of the image (actually, I had just merged layers and increased dpi from 300 to 600, and had just saved and reopened the file, so in fact at the moment when the problem occurred there was only one layer). The purpose of my Skew operation was to correct a remaining perspective distortion and restore vertical parallel linearity to the image.
Photoshop CC froze during the skew operation, although some functions remained; it would not allow me to save the file or to complete the skew operation. There was plenty of space left for my scratch file, and I was allowing PS CC just over 10 GB of working RAM.
MORE DETAIL: I could not complete the Skew action. Clicking on the "Move" tool to complete the skew resulted in error tones and a refusal to respond to most other commands, including "Save", although it accurately displayed all distortions of the image that were attempted as part of the Skew. It simply refused to complete the skew or to let me access the functions of most other "click-on" commands via their icons.
I cancelled the skew manipulation via keyboard using "Command-." and I then tried other actions to test the responsiveness of PS CC. After Skew was cancelled, all other actions that I attempted with the file were allowed.
I then stepped backward (using History) to the point where I had attempted the Skew, and, again it froze when I attempted to complete a skew. The screen DID show the skew manipulation taking place, and I could change screen magnifications by entering a new percentage on the lower left of the image screen, and I could move the viewing position of the image back and forth successfully at each magnification to check the accuracy of the perpindicularity of the lines against the sides of the image window frame. However, any attempt to actually complete the skew was refused. And, again, I had to cancel the attempt with Command-. I then closed and saved the image in its pre-skewed form (essentially, in the same form and state in which I had opened it).
I tried it all over again after quitting and restarting PS CC and reopening the image from scratch -- and still got a freeze when I attempted the Skew operation.
Finally, I closed PS CC and opened the same image in Photoshop CS6 Extended (13.1.2 x64). I was able to complete the Skew operation exactly as I had attempted it in PS CC, and this time there was no problem. That was the last "step" in preparing my file for use, and so I then saved it in .psd and .jpg versions --
...and I immediately proceeded to file this Report. Hope this is helpful.
I'm able to skew a letter sized document at 600 dpi with only a single layer (not the Background layer) without issue. Perhaps a screen shot of what you are seeing when the skew refuses to apply. I'm wondering if Photoshop is waiting for some type of input to finish the skew for some reason.
Are you talking about the Skew filter, or Free Transform?