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Technical Core Optimization: bukkit.yml

The bukkit.yml file serves as the fundamental configuration registry for your server’s API layer. While often overlooked in favor of world-specific settings, tuning the variables within this file is essential for reducing CPU overhead and maintaining a consistent 20.0 TPS (Ticks Per Second) during peak community hours. This guide focuses on optimizing the three primary technical pillars of the Bukkit engine: entity limits, chunk lifecycle management, and spawn calculation intervals.

Difficulty

Intermediate

Time

6 Minutes

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Strategic Spawn Calibration

High entity counts are the primary contributor to server-side lag. By reducing the maximum number of simultaneous mobs allowed per player, you can drastically lower the CPU cycles required for pathfinding and AI logic.

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1. Defining Spawn Limits

Locate the spawn-limits object and apply these high-performance values: 
spawn-limits:
  monsters: 50      # Default 70 | Significant TPS improvement.
  animals: 10       # Default 15 | Reduces passive entity load.
  water-animals: 3  # Default 5  | Minimizes unnecessary ocean calculations.
  ambient: 1        # Default 15 | Essential for reducing Bat entities.

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2. Throttling Ticks-Per-Spawn

The engine defaults to calculating new monster spawns every single tick (20 times per second). This frequency is generally excessive for survival gameplay.
  • monster-spawns: Set this to 4 (Default 1). This instructs the server to calculate spawns every 4 ticks, reducing the AI processing load by 75% without visibly affecting the difficulty for players.

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Technical Chunk Management

Managing how the server handles memory recovery for unloaded chunks is important for preventing RAM bloat.
  • Chunk Garbage Collection: Locate the period-in-ticks variable.
  • Recommended Value: 400 (Default 600).
  • Technical Result: Lowering this value ensures the server checks for and purges empty, inactive chunks from memory every 20 seconds instead of every 30, expediting RAM recovery following player movement.

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Interaction with Paper MC

If your server uses the Paper Modloader, many of the values defined in bukkit.yml serve as “Fallbacks.” Paper implements its own advanced logic within paper-world-defaults.yml. We recommend optimizing your Bukkit core first, then proceeding to fine-tune your Paper-specific variables for the ultimate performance profile.

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Need Extra Help?

If you encounter any issues, our support team is ready to assist:

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Last Updated: January 2026 | Minecraft: Core performance tuned.