bad optimization in this beta/preview.

In the overworld, the FPS have a drop between 30-23 FPS.

In the nether, the FPS they drop a lot reaching up to 15 fps.

In the End, the FPS is a bit stable but compared to the previous beta, it suffers from a drop in fps depending on the situation.

For example, if the End is empty except for only the dragon, the fps rate is between 41-29 fps.

If the End has mobs or entities the End has a fps rate of 36-25 fps, including the Ender Dragon, if there are only endermans or other mobs/entities there will be a small fps boost.

Also having items like patterned banners causes the game to freeze momentarily.