I have a Zombie Spawner below my base and it goes up to like 20 Zombie's and then nothing will spawn anymore, if I place down a mob from a Safari net I hear the sound of the mob for like a second but the mob despawns instantly. Please Increase the mob limit, we have no lag anyway on the server and when we have the most people online it's usually around 10 people with no lag. (Picture included showing how much mobs are the limit).
If you have twenty mobs in one space you'd need to kill them much faster as you're hitting the per chunk limits in that case.
