Mob rendering

Whenever a the player is inside a large number of mobs the transparency effect caused by going close to a mob seems to struggle as the game lags hole inside all the entities. I recreated this by making a creative world and summoning a large group of mobs in one place. Going near them didn’t crash the world or cause lag but going inside them or close enough to render the transparency caused major lag and I couldn’t move for up to five minutes at at time it took me a while to escape from the lag.