MobStacker is a smart plugin that stacks mobs to improve your server performance when having many farms or spawners. You can set a threshold to prevent stacking mobs if there are only a few and a blacklist to protect important mobs like Villagers.
Everything is configurable.
ALL THE FEATURES
Stack mobs that are in farms or spawners to reduce lag and improve server performance
Customize the plugin to set a minimum number of mobs for stacking and to exclude certain mobs from stacking, such as Villagers
View statistics and reload the configuration with simple commands