You aren't taxing it much.
Maybe it is cpu bound.
memory can be in use but not 'used' as well, as applications are aable to they will load and work on data files in memory and with more memory hold more data in RAM.
if each process (and an application can have more than one process or thread or child process) each of which may want to grab and allocate memory.
CS6 is one app where 24GB is a good starting point, but some users bump it up to 48 or 64GB RAM.
pageouts are a sign an app or OS is starved not that it has enough or ideal amount.
32-bit apps were limited to allocating 3.5GB per process, and address space.
if you have 4x2GB then realize that 3x8GB or 4x8GB for some users and applicatoins is common.
All your drivers, plug-ins and such should be 64-bit capable.
making extensiosn and drivers and plugins that were 32 and 64-bit was clumbersome and more work. Being able to be Intel only 64-bit applications means that some things like TurboTax 2012 this year would only run on 10.6.8 and above because it used new compilers and code which should make for more stable easier to test and run better.
Graphic cards were also being limited by 32-bit it seems and having Graphic cards for some reason with more than 1.5GB VRAM then 2GB, while drivers are just beginning to allow and make better use of 3 and 4GB VRAM.
I have no idea what the hardware requirements in the future for higher resolution and higher def video will be but they can now begin to and all this talk of 4k format.
