The world has new lighting, and it is switched on for everyone.
The sun and the moon now cast shadows from trees, bushes, houses and fences, and you see them much further around you. At night, street lamps, lanterns and windows light up the ground and the people near them.
Characters and monsters are now drawn by your graphics card, which takes work off your processor.
You can switch the new lighting off in Video settings (Improved lighting).
Start the launcher to get the update.