My Nether is REALLY laggy.

EVERYTIME I go to the Nether... my Minecraft gets really laggy when I move, and also it's really hard to move... I attacked a Ghast and when the Fireball exploded... my game freezed for 1 min. <-(EXTRA)

Is this a bug or what? Because I have the Latest Java and it stills happening, also with my OptiFine happens... Can you help me? (I selected Survival... It really happens to me with ALL the GAMEMODES).

P.S.: It happens with EVERY WORLD and happens too with the Nether Fire (When I get close).