I'm surprised this hasn't been made already:
All this plugin does is make it so that when a player/mob dies, the orbs get deleted almost instantly, virtually removing them from your game. No More Lag!
Download the plugin and put NoOrb.jar in your plugins folder, and then restart your server or type /reload in the console - It's that easy.
This was just a small 10 min project, but I decided to release it because I know some people will use it.
No commands, no permissions, no lag, no worries.