Extreme Optimization for Minecraft

If you've already optimized YML files and still lag, read here.

Java Startup Flags

Don't use default flags. Use Aikar's flags. They are tested and work. Make sure to use Java 21 for the latest versions.

World Pre-generation

50% of lag is caused by chunk generation. Use the Chunky plugin to pre-generate the whole world before opening.

MySQL Database

If you use flat files (JSON/YML) for player data, you'll have trouble. Switch to MySQL or MariaDB and optimize the connection pool.

Conclusion

Lag kills servers. Invest time in technical infrastructure.