It was never designed for mobile and I am quite surprised it even works. Once it gets near end of development i can try do some optimisation for those who find it too laggy.
Response to tao pet comments:
I've intentionally made it so you can only summon it once during a fight. It would be a bit OP in the linear fight format if you could just keep summmong it as it could block anyone else from taking damage. You need to heal your pet and keep it alive just like any other character.