My understanding of Win10 is that it fixes most of the worst mistakes of Win8 and Win8.1, adds a few clear improvements over Win7 (like less bad use of large memory, and some basic virtual desktop support that has some of the features X got about three decades ago).
However, every new version of Windows screws with all the settings and organisation - it is a real pain. And every new version breaks /something/ that worked fine before (in my job, I have a lot of unusual programs).
As for speed differences between Linux and Windows - yes, Linux (especially with a lighter choice of desktop) is far better on more limited systems. But run Firefox or Chrome, and the browser will take far more resources than your OS and desktop regardless of the system - it is usually the apps that use resources, not the OS.
I pick Linux rather than Windows for most purposes, simply because it is a far better for most of the kind of things I want to do. (And I appreciate this doesn't apply to all users.)