Fire up the Task Manager and you may see 'System' taking too much of your precious RAM? In our example, it's around 650 MB and, at times, this number spikes to as much as 1.5 GB. That's a large amount of system memory. So, is Windows 10 just really inefficient? No, not really.
Microsoft started optimizing the OS and the amount of memory Windows consumes with Windows 8, bringing it down significantly compared to Windows 7. Given that the same OS was expected to run across PCs and RAM-starved tablets, this was a much needed improvement. Following in that vein, Microsoft has made certain changes to the way Windows 10 handles RAM with the new Insider 10525 build.
Basically, the reason you're seeing such high usage of memory is that, instead of writing pages to your hard drive after they've been unused for a long time, Windows now compresses them, while still storing them in the physical memory. That's what the 'System' usage shows in Task Manager. In Gabe Aul's words:
In Windows 10, we have added a new concept in the Memory Manager called a compression store, which is an in-memory collection of compressed pages. This means that when Memory Manager feels memory pressure, it will compress unused pages instead of writing them to disk. This reduces the amount of memory used per process, allowing Windows 10 to maintain more applications in physical memory at a time. This also helps provide better responsiveness across Windows 10...This is visible in Task Manager and the reason the System process appears to be consuming more memory than previous releases.
So, next time you see the system taking too much memory, don't worry; Windows is more efficient than ever. Compressing data stored on RAM is a technique becoming increasingly more prevalent and OS X and Linux already use some form of a 'compression store'. With this improvement, not only are you able to work faster but can hold more data simultaneously. That's a win all around!