Windows 8 not only has the ability to suspend Metro style apps when they are not in use, but it also has an impressive hibernation and quick resume technique that will allow the operating system to reduce memory usage for other applications, without affecting to switch back to the suspended app — all in less than a second.
Previously, Microsoft outlined the work they’ve done improving power efficiency for Windows 8 Metro style apps by suspending apps when they are not being used — this will save power and system resources –, but now the software giant is expanding and showing how all this actually works — Not to be confused, this new technique will only work with Metro style apps from the Windows Store and not with traditional desktop apps, because of the nature of how these kind of applications need to access system memory –. Essentially Metro style apps can efficiently reduce memory usage while they are suspended. Apps that need to do work in the background will be able to take advantage of scenario-specific multitasking APIs (application programming interface), this will enable the end-user to run many applications at the same time without impacting memory usage or compromising a fluid experience.
Reclaiming memory from suspended Metro style apps technique
There is no way around, Metro style apps will still allocate a space in memory in order to operate. What is impressive is that Microsoft has developed a method to reclaim used RAM memory from apps that has been suspended without terminating them.
This is how it works: When Windows 8 or an application needs additional memory and the system is reaching to its memory limit, then the OS will grab the private working set (reserved memory space used for a particular application) from a suspended app and write it to the disk, making possible to reduce memory usage for another Metro style app that made the request. This is not totally brand new, Microsoft has been using a similar technique for a long time to hibernate Windows, to save power and resume as quickly as possible without the need of restarting the computer.
Microsoft says that many apps will take less than a second to write back the working set of a suspended app back into memory. The resume time will also depend on many factors such as disk speed and size of the app in question, but the company is trying to optimize this new feature to make it more efficient.
If you want to see this feature in action, watch the video below or try it yourself as this technique is already part of Windows 8 Consumer Preview.
Source Building Windows 8