I am using Lightroom CC 2015 on Windows 10. But I still have my Lightroom 4.4 installed. I turn to it from time to time, but primarily as a reference to enable me to answer some questions, such as this one. I have played with Lightroom 4.4 a little bit. I do know that the slideshow module works fine. But I have not done any extensive editing with it. Based on my limited use, I would say that Lightroom 4 will run fine on Windows 10. If you run the upgrade advisor (or whatever it's called) it will tell you if you have any software that is not compatible. I have had no problems with any of my previous software since moving to Windows 10.