CobbleStacker is a server-side Fabric mod for Minecraft 1.21 designed to significantly reduce entity lag by intelligently stacking mobs, ground items, and spawners. Fully compatible with Cobblemon — all Pokemon are
automatically excluded from stacking.
Mob Stacking
- Automatically merges nearby identical mobs into a single entity with a visible nametag (e.g. "x16 Zombie")
- Respects mob attributes: variant, color, size, baby/adult, tamed owner, profession, and more
- Configurable death behavior: KILL_ONE (kills one and respawns the stack with reduced count) or KILL_ALL (kills the entire stack with multiplied drops and XP)
- Entities with name tags can be excluded from stacking
- Blacklist support by entity type and world
Item Stacking
- Merges ground items of the same type beyond vanilla limits (up to 1024 per stack by default)
- Custom nametags showing the real item count
- Built-in auto-clear system that removes old item stacks after a configurable time, with a whitelist for valuable items
- Manual clearlag command for instant cleanup
Spawner Stacking
- Stack multiple spawners of the same type by right-clicking with a spawner in hand
- Floating hologram displays the spawner type and stack count
- Mobs spawned from stacked spawners come out pre-stacked
- Silk Touch support for spawner drops
- Automatic spawner property repair to prevent broken spawners
- Persistent data saved to JSON
General
- Fully configurable via cobblestacker.json
- Admin commands: /cobblestacker reload, stats, info, kill, clear, clearlag, debug, fixspawner, setstack
- Lightweight and optimized with batch processing, caching, and minimal overhead
- No client-side installation required
