Click on the "less effects" option in the options menu.
Try turning off day and night cycles as well as weather effects, that might help.
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It should appear in the regular options menu. But then again, the options vary with the device you use, so I'm not the guy to turn to, as I use Apple (lmao).
Try asking Mikey, he's more qualified to answer you than me, 'cause I doubt my gfx will be able to make you lag less.
I have an iPad air 2 and never experienced lag on it
I have an iPad mini 2 and it works great for graal.