It's really clunky to play on mobile. I'm stuck on the lowest graphics preset too, so I can't make out enemy movements at all. I never dared crank the settings higher to keep the game running smoother. I probably messed up my timing on defense, I still take 6 damage whether I hold up my shield or not, and I'm on easy mode by the way.
But after taking a closer look, my setup is totally more than powerful enough, so there shouldn't be any other issues.