For a couple of decades, it seemed like every time a new version of Windows was released, its hardware requirements would keep pace with hardware advancement, necessitating sometimes-costly hardware upgrades if you wanted to stay up on the latest software. Nowhere was this more evident than in Windows Vista, which launched in 2007 on hardware that wasn't always prepared to deal with its increased memory and graphics requirements.
This trend has been turned on its head in recent years, at least in part by the popularity of small computing devices with comparatively little processing power. Netbooks filled this role during the Windows 7 era, and tablets are filling it now. In order to support them, Microsoft's stated goal with both Windows 7 and Windows 8 has been to keep the operating system's performance and resource usage level between versions. New features can be introduced, but only if the software can be tweaked so these new features don't drive up the hardware requirements.
We've already done some testing of these claims in our full Windows 8 review, where we saw that the new operating system's performance was broadly similar to Windows 7's. In this piece, we'll be diving just a bit deeper, testing things across multiple systems to get an idea of how Windows 8 will perform on more diverse hardware.
Source
A Guy