Implement the ability to toggle spawners on and off. The spawners will physically remain in place and count towards your island limit but will not be able to spawn mobs. Why? Most people who have mob grinders do not remove spawners from them when not in use. Likely because; they take time to manually remove, fear of losing spawners (have a tendency to fly away) and the 30sec cooldown when redeploying then. Around 75% of my own spawners are running inefficiently right now. According to Spork’s reply to this, mob spawning uses approx 5% of server resources, plus the mob drop entities being processed by redstone machines. Could be implemented via a new command or through a lever attached to spawners (acting as a toggle). Pro: Sizeable performance improvement Con: Implementation cost If something like this already exists, let me know!