ARS Technica discusses some of the technical improvements that Microsoft made in its new operating system. It includes the sandboxing of apps, power saving technologies, a tickless kernel, better security, slimmer memory usage, and more.
Just as is the case with the user interface, many of the improvements made to the Windows 8 core are motivated by Microsoft's desire to transform Windows into an effective tablet operating system. Even those of us with no interest at all in tablets can stand to take advantage of these changes, however. For example, Windows 8 is more power efficient and uses less memory than Windows 7; while such work is critical to getting the software to run well on low-memory tablets with all-day battery life, it's equally advantageous for laptop users.