A while ago I was running Windows 10 as my main operating system and noticed now that when I downgraded back to Windows 8.0 that some apps actually seemed faster launching and running compared to Windows 10, is this normal or is this because my computer is older.
In some cases Windows 10 will run better if you do a clean of Windows 10 install rather than upgrading from Windows 7/8. So, a clean install may make it run as fast as or faster than Windows 8. With some older hardware, some people find that Windows 8.x runs faster than Windows 10. Unless you are prepared to start from scratch and do a clean install of Windows 10, staying with Windows 8 (and upgrading to 8.1 if you haven't do so already) would be a better choice in my opinion.