You've tried even the dll solution and still didn't work?
I totally feel you, I was where you are, was searching for days for a solution and just when I said I give up, I fixed it
Is the High Cpu incident occur when playing normal Diablo 2 also?
If you open Median on window mode and you click out of the game (so the game is like in a minimized state) is Cpu still that high or is it dropping down?
My advice, is to try fixing your problem out of D2SE first (I mean with normal launcher).
Don't forget to check the Override DPI scaling box and try all three options. From my experience this thing is TOTALLY messing almost everything on Windows 10.
Waiting for your feedback. I hope we can make it work!