For any of you who are using Mavericks, it is important to note that its memory management is very different than that used in previous versions of OS X and hard won knowledge in those versions can be misleading or even wrong in Mavericks. One thing that causes new Mavericks users consternation is Mavericks memory management works hard to keep the RAM memory chock-a-block full. The idea being that even if an application in RAM is not currently being used, it may well be used again soon so the RAM it occupies is compressed to make room for other applications that are running and need the RAM. Compressing or decompressing the RAM takes only a small fraction of the time required to push data to the Swapfiles.
In Mavericks Activity Monitor, there is a horizontal box at the bottom of the window labeled Memory Pressure. If it is green you have all the RAM you need, if it turns yellow the system is pushing the limits of the existing RAM, but when it turns red you either need to shut down some running applications or add more memory. Actually it is a lot simpler than previous OS X VM management iterations in addition to offering noticeable VM performance improvements.
