LR Classic says Windows 7 is a minimum requirement but it also says you need directx 12. Windows 7 does not support directx 12, so....
I just installed LR classic and I get some long 'pauses' when I try to do anything. After the pause it runs fine for that picture. When I do a system info it says I don't have opengl support, which I do. I am running an i5-4570 cpu and intel 4600 graphics.
I also found the support for the HD4600 to be dropped.
However, the HD4600 anyway is not so powerful to see a gain over using the CPU - depending on the resolution of your monitor .. which is .. ?
My monitor is a 1920x1080. My problem was the long delay I was getting. I said the heck with it today and rebuilt the computer to windows 10, it is running fine now.