This a priori so interesting feature is by no means new, although of course it is updated compared to another that has already appeared in the 90's called Ram Doubler that the Connectix company presented and was neither more nor less than a technique to compress Ram memory and that we did not see ourselves in the commitment to expand virtual memory and that the system had to access the hard disk more times than desired, slowing it down all.
Indeed Ram Doubler worked perfectly and practically increased the effectiveness of the Ram by almost twice with the same number of programs and processes running handling amounts of memory that today would seem ridiculous, between 8 and 32 Mb of Ram. Now this feature rears its head again in OS X 10.9 although of course with improvements and a much greater capacity.
With memory management, this feature went down in history since it was not necessary to compress memory when having software able to manage it automatically and not overload it although it did not always work well and you had to pull other programs to free memory. However, with the appearance of OS X Mavericks it is re-integrated making use of memory compression.
In the current version of OS X Mountain Lion, what the system does is point out all the content that has been run, even those programs that are open but not active and as we open more and more programs, of course, memory will decrease since everything "spends" to a greater or lesser extent.
The new memory compression works by using a dictionary-based WKDM algorithm which uses multiple cores of the computer's CPU to reduce memory use in idle applications, reaching 50% savings in the best of cases, which is already a considerable amount of memory.
When the software is fine-tuned and old ideas are taken up for integration into new features, it results in a better use of resources And that is always appreciated.
More information - Microsoft Office 2011 is updated to version 14.3.5
Source - Appleinsider
And if I deactivate compression, what would happen?