Microsoft knows that many of us use laptops rather than desktops these days and we also want to use a lot of apps at the same time. They also know that more memory equals more RAM, which means more battery usage, which in turn means lower run times for our laptops. So, what Microsoft has done is to identify ways to free up memory requirements and still have an efficient and effective operating system.
Microsoft has developed a way of combining memory so that memory takes up less space. What normally happens is that when you install an application, it will allocate some extra memory to that app in case you need it in future. Install lots of apps and you have lots of sets of allocated memory just sitting there, doing nothing, but taking up valuable memory space. By using memory combining, Windows 8 assesses the actual memory needs of an app and then deletes all duplicate memory entries across the system memory. In this way Microsoft has managed to free up to 100MBs of memory.
By looking at Task Manager they saw that using Windows 8 dramatically reduced the amount of memory needed by the OS. CPU usage was reduced by 4% and physical memory by 12% as attached.