Lag with the gold farm

I saw the new way to brake threw bedrock, so i decided to make a gold farm. Unfortunatly when i made it the Pigmans were lagging. When I were eating, i needed about 10 seconds to finish the beef. The fps does not drop. I forgot to mention that before i made them aggressive, they were not lagging. When i hit a pigman in the nether(but not in the farm), it wasnt lagging too. I guess it is something with the entities