Hi!
It's hard to say what the problem is. The first launch may take some time, but repeated launches of the game should be quick (i use win10 too).
I can advise you to open the data/chr.ini file in notepad and add a new line with the text dev=1
This can be done after the line id=1 or after login=1
After starting the game, new options will appear (fullscreen and async). Perhaps they will help.
P.S. I do not recommend enabling the save option.