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Tuning the Engine: Startup Flags

Minecraft operates within the Java Virtual Machine (JVM), a specialized environment that manages memory and execution logic for the game. By providing specific technical instructions (flags) during the startup sequence, you can dictate exactly how Java handles memory allocation and “Garbage Collection” (GC). Correctly tuned flags are essential for eliminating micro-stutters and ensuring consistent performance, especially on servers with high player counts or complex modifications.

Difficulty

Intermediate

Time

5 Minutes

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Aikar’s Flags: The Professional Standard

Developed through years of community-driven empirical testing, Aikar’s Flags represent the gold standard for Minecraft server optimization. These arguments prioritize frequent, minute memory cleanups over infrequent, massive ones, effectively preventing the “stop-the-world” pauses that cause noticeable in-game lag spikes. If your hosting tier permits custom startup parameters, we recommend using the following string: 
-XX:+UseG1GC -XX:+ParallelRefProcEnabled -XX:MaxGCPauseMillis=200 -XX:+UnlockExperimentalVMOptions -XX:+DisableExplicitGC -XX:+AlwaysPreTouch -XX:G1NewSizePercent=30 -XX:G1MaxNewSizePercent=40 -XX:G1HeapRegionSize=8M -XX:G1ReservePercent=20 -XX:G1HeapWastePercent=5 -XX:G1MixedGCCountTarget=4 -XX:InitiatingHeapOccupancyPercent=15 -XX:G1MixedGCLiveThresholdPercent=90 -XX:G1RSetUpdatingPauseTimePercent=5 -XX:SurvivorRatio=32 -XX:+PerfDisableSharedMem -XX:MaxTenuringThreshold=1 -Dusing.aikars.flags=https://mcflags.emc.gs -Daikars.new.flags=true

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Strategic Memory Allocation

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Synchronizing Xms and Xmx

A fundamental best practice is to set your Minimum Memory (Xms) equal to your Maximum Memory (Xmx).
  • Technical Reasoning: If these values differ, the JVM will constantly attempt to resize the memory heap based on immediate demand. This negotiation with the operating system consumes CPU cycles and frequently triggers lag during the resizing process. By setting them to the same value, you pre-allocate the entire heap upon startup, ensuring total stability.

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The OS Overhead Buffer

When allocating memory to the JVM, you must leave sufficient resources for the underlying Linux operating system and the Game Panel’s background processes.
  • Recommended Limit: For a plan with 12GB of total RAM, do not allocate more than 10.5GB to the Minecraft process (e.g., -Xmx10500M). Maintaining a 1GB to 1.5GB buffer prevents the host node from forcefully terminating your server due to out-of-memory (OOM) errors at the OS level.

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Integrated Platform Optimization

At FREAKHOSTING, our Premium and Extreme instances include these technical optimizations automatically at the panel level. You typically do not require manual flag entry unless you are deploying a highly specialized modpack or a proprietary server jar.

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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 | Java: Optimized for Minecraft.