This is the same problem I was having on my Laptop. but now on the new iMac I will have 8 GB inactive ram but will experience Page outs in the Activity Monitor. The problem is causing slow cpu and the need to us the purge command in terminal to enable to keep working This of course when using AP or Photoshop with large images and a repeated action to all. For example when exporting 188 images from Ap as 16bit files. Bad Memory Management! Hopefully 10.9 memory management is better