I think that the reason for Ys VIII running this badly on the Switch is less about the Switch, and more about NIS America. Have you seen their PC port of Ys VIII? It's laughably bad, and several patches of fixes haven't even gotten close to making it a good port.
I WON A BET AGAINST AZUREN! WOOOOOOOOOOAAAAAAAAHHHHHHHHHHHHHHHHHHH
:3