I'm seeing an improvement in 10 over 8, but I assume that a lot of that is because my Windows 10 install is fresh and doesn't have a lot of junk in it that my Windows 8 install does.
I remember that I found the same when I installed Windows 8 when I was running 7, I thought wow this is fast.
Later on it did't seem that much different.
It's hard to attribute whether the difference has anything to do with the OS or not, but even my games are running better.