Chickens that either walk into caves or spawn in them lay eggs. This wouldn't normally be a problem, but some zombies can pick up items, and when they do pick up an item they don't spawn. I've noticed on several servers that caves and ravines near spawn or any active place tend to have hordes of zombies stuck in these caves that won't despawn because they're holding eggs.

I realize that such an amount of mobs can really run havoc on a server, or even a singleplayer world. All a greifer would need to do to slow or crash a server is to find a zombie spawner and place a few dozen chickens in it and wait. Even if he left the zombies would still be there due to them holding an item

I know this isn't technically a bug, but it is something that has a lot of potential to slow/crash servers. All that's needed is a simple fix that would not allow zombies to pick up eggs. I hope this gets some attention, and thank you for reading this.