So far, both seem much better on W10. If you do see a change to the slow side, you need to talk to the upgrader (you?) about post upgrade work. Drivers, apps, etc.
I've upgraded two systems: 1 laptop, 1 desktop from Win 8.1 Pro 64-Bit to Win 10 Pro 64-Bit and generally am pleased with the results. One area of utter frustration, though is with Edge and IE11 browsers, respectively: a) Edge's sparse features compelled replacing it with IE11; b) IE11 seems to perform slower and is less reliable than on Win 8.1. I've decided that a new browser is indicated, and the net posts seem to favor Chrome. While I use Chrome on my iPAD, it's never been used on any of my Windows systems. Any information on Chrome's behavior on Windows 10 is most welcome.