Minecraft wiki entry for Development_versions, associated text: New data-driven items:
Turtle lightning interactions are now data-driven.
Pufferfish puffed states are now data-driven.
Brewing stand potion recipes are now data-driven.
Changed Breathable, RideTick, and Transformation systems to use ViewedEntityContext.
Added precompiled header targeting for ScriptAPI.
Significantly increased the maximum spawnRadius distance.