Understanding Startup Flags

Optimize your server's Java Garbage Collection with Aikar's Flags.

What are Startup Flags?

Startup flags are arguments passed to the Java Virtual Machine (JVM) when your server starts. They control memory allocation and garbage collection behavior. Using the right flags can significantly reduce lag spikes.

RYN Host Default

At RYN Host, we pre-configure all servers with Aikar's Flags, which are widely considered the industry standard for Minecraft performance. You typically do not need to change these.

Aikar's Flags Explained

-XX:+UseG1GC -XX:+ParallelRefProcEnabled -XX:MaxGCPauseMillis=200 ...

UseG1GC: Uses the G1 Garbage Collector, which is optimized for large heaps and low pause times.
MaxGCPauseMillis=200: Tells Java to try and keep "stop-the-world" pauses (lag spikes) under 200ms.
AlwaysPreTouch: Allocates all RAM to the OS at startup, preventing lag during gameplay when the server needs more memory.

How to Change Flags

Go to the "Startup" tab in your panel.
Look for the "Startup Command" or "Variables" section.
Warning: Changing these incorrectly can prevent your server from starting. Only modify if you know what you are doing.