Modded Minecraft Knowledge Book Help

Java Arguments

Arguments are optional parameters added to enable / disable certain functions of a program.

Performance

Use these arguments to potentially improve performance of Minecraft:

  • -Xms | -Xmx-> These values set the Minimum and Maximum amount of RAM memory Java is allowed to use.
    It's not recommended to allocate more than 10 Gigabytes unless using Shaders, using too much RAM will potentially overload the Garbage Collector.
    Example usage:
    -Xms4g -Xmx4g-> 4 GB
    -Xms6g -Xmx6g-> 6 GB
    -Xms8g -Xmx8g-> 8 GB
    -Xms10g -Xmx10g-> 10 GB

    For most ModPacks, 6 or 8 GB is plenty.

  • -XX:+AlwaysPreTouch
    In Minecraft context
    Reduces stutters during gameplay.

  • -XX:+UseStringDeduplication
    In Minecraft context
    Saves RAM memory on repetitive string objects, like Block names.

  • -XX:-OptimizeStringConcat
    In Minecraft context
    May improve performance in heavy string usage, such as Logs, Chat, and Mod internals.

Setting Arguments

If using a Launcher, you can set Java args in the settings, or for individual Instances.

02 October 2025