Lag spike while loading player head textures / player skins
End crystals placed on exit portals generated before 1.9 do not respawn the ender dragon
Credits background jitters
Structure block data length limited to 12
Intersecting structures can create corrupted block entities (spawner / chest)
Shifting around servers in the server list crashes the game (
ArrayIndexOutOfBoundsException)
Leaves change to stone near Lava Pool (Recurrence of MC-48340)
End Portal Frames change to Stone near Lava Pool
Angering passive mobs in new nether chunks very far away from previously generated chunks, then entering a nether portal causes server to completely freeze
Setting the weight in Template Pool to high values will lag world and can cause out of memory error.