I am currently running a Mac with OS 10.8.2 and have installed Adobe CS 5.5 Production Premium. Within Photoshop- Preferences- Performance, Photoshop is only recognising 2100MB of RAM, while my Computer has 16GB of RAM available. I have checked and according to the OS Finder, this 16GB is active. I have also checked across other Adobe programs such as Adobe Premier and have confirmed that here it is also recognising the Available 16GB of RAM. Thus it is only in Photoshop that this is occurring. I have since deleted all of my preferences from both the user level and the hard drive but no recification. I have noticed a recent discussion which sounds very familiar, http://forums.adobe.com/message/4823440
however this is on a windows based system and the last suggestion from a user was to a windows related issue and I am not sure that fixed the issue for them or not.
Anyway I would appreciate and help or suggestions on this matter as I can't even draw a path at the moment without PS crashing or freezing up.