Your IGN: GoogleImaged
Server for the suggestion: Survival
Suggestion: Get a plugin that stacks mobs
Reason why it should be added: This should be added for spawners because it will create less lag which everyone needs.
Most Mob-stackers do not drop extra XP for killing them, rendering most grinders useless.
Additionally the only mob-stacker that i can find that's stable and updated is 5 Bucks. It doesn't even appear to support XP.
So i'd ether have to write one from scratch or make everyone with an XP grinder very displeased.
The only way for the XP feature to work is by killing each one individually, Rendering Sweeping Edge almost useless.
The majority of lag on servers comes from Redstone, Piston-Physics and Lighting-updates. The latter of what is only caused by Blazes, Ghasts, and the Ender Dragon.
While it is true that mobs contribute to some lag, There are better ways of "fixing" it, One being disabling the AI's of mobs spawned from spawners. (Dummies if you will) as Pathfinding does contribute to a lot of CPU
Another way to reducing mob-lag is by disabling Mob on Mob collisions (Restoring behaviour to pre-1.9)
I don't like killing Vanilla Game features, then its no longer a Minecraft Survival Server, will always attempt to keep as many as possible.
I will not add this.