Minecraft wiki entry for Development_versions, associated text: Performance improvements.
Skin picker no longer shows the silhouette of the skins behind it when choosing a custom skin.
Tweaked mouse sensitivity for vertical vs. horizontal motion in UI in Rift (Win 10 Rift only).
Increased maximum view distance for capable GPUs (Win10 and EDU only).
Tweaked the clock texture, so it has all the correct pixels.
Old world type option
Not shown anymore.
Old worlds created earlier still can be made infinite.