Ok...So the bug is : I never had lag before 1.8, now I have a looooot of it. Especially Tick Lag that makes Horses, Minecarts, Beacons, Boats.... Useless...And people say we can't go back to 1.7.10 without losses 😞.
New dungeon was supposed to spawn in 1.7-generated chunks, they are not on my server :/.But the Guardian mobs are spawning (not the elder one).
Actually, the problem is the same if the block under the Slime isn't a piston.
Ok...
So the bug is : I never had lag before 1.8, now I have a looooot of it. Especially Tick Lag that makes Horses, Minecarts, Beacons, Boats.... Useless...
And people say we can't go back to 1.7.10 without losses 😞.