but Windows is so astonishingly terrible on handhelds
The way you are telling me this reminds me of the old HP windows laptops I used to use that their battery life did not even last 2 hours lol (I eventually got a MacBook Pro and that was a massive upgrade).
I still don't picture windows doing that great with laptops (as in optimization), but I don't know, I have seen very good laptops with good specs very recently that it could maybe make up for Windows being not optimized for anything.