Hi! One of the devs here. I noticed that the game ran pretty slow on my phone as well (Samsung note 5). We'll definitely have to do some optimization to get the game running faster, sorry about that! As the for the inventory arrows, I never actually hooked them up so they don't work... But you can scroll the box by placing an item on the crafting board and swiping on that spot (haha). We'll get this all fixed soon!