Too much lag. I can barely move . Had to delete world an state a new one. Affects all versions.

I've had this happen 6 time already and very time I get angry and delete the game. I get to fill diamond armour in one of my world's , I need xp so I make an xp grinder using a spawned. I left it for a bit to let the skeletons fall down to where i can hit them. I come on the game to kill them but what do I find its full of lag, so much so I can't even move.Samsung Core prime.