Microsoft is doing a lot of things with Windows these days, most of which is focused on the core Windows 10 experience—the first of two majors updates scheduled for this year will start rolling out any day now. In addition, Microsoft appears to be working on a stripped down version of Windows 10 called Windows 10 Lean that will focus on performance

Source: Hot Hardware – Windows 10 Lean Redstone 5 To Ditch Superfluous Features For Better Performance