The objective is to utilize ZGC (Generational) or Aikar’s G1GC Flags to maintain sub-50ms tick rates ($T_{tick}$) while preventing the RAM from becoming a performance anchor.
1. The 2026 Choice: G1GC vs. Generational ZGC
With Java 21 and Java 25 becoming the standard in 2026, you have two primary paths for a high-RAM machine.
| Collector | Best For… | Technical Advantage |
| G1GC (Aikar) | Most Servers / Modpacks | Highly stable; predictable “Mixed Collections” for Minecraft’s object-heavy load. |
| Generational ZGC | 16GB+ Heaps / Extreme CPUs | Ultra-low latency (<1ms pauses); handles massive memory pools without stutters. |
2. Optimized Aikar’s Flags (The Industry Standard)
For most Paper, Purpur, or Fabric servers, Aikar’s flags remain the king of stability. We have tuned these specifically for a high-memory environment ($V_{mem} > 12GB$).
Recommended Arguments:
java -Xms16G -Xmx16G -XX:+UseG1GC -XX:+ParallelRefProcEnabled -XX:MaxGCPauseMillis=200 -XX:+UnlockExperimentalVMOptions -XX:+DisableExplicitGC -XX:+AlwaysPreTouch -XX:G1NewSizePercent=40 -XX:G1MaxNewSizePercent=50 -XX:G1HeapRegionSize=16M -XX:G1ReservePercent=15 -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 -jar server.jar nogui- -Xms & -Xmx: Set these to the same value (e.g.,
16G) to prevent dynamic heap resizing, which causes lag spikes ($L_{spike}$). - G1HeapRegionSize=16M: Doubled from the 8MB default to handle the larger 16GB+ heap more efficiently.
3. The “Extreme Performance” ZGC Config
If you are running a high-player count server on a modern CPU (AMD Ryzen 9 or Intel Core Ultra) and using Java 21+, ZGC is superior for avoiding micro-stutters.
Recommended Arguments:
java -Xms24G -Xmx24G -XX:+UseZGC -XX:+ZGenerational -XX:+UnlockExperimentalVMOptions -XX:+AlwaysPreTouch -XX:+ParallelRefProcEnabled -XX:+DisableExplicitGC -jar server.jar nogui- -XX:+ZGenerational: This is the game-changer for 2026. It allows ZGC to treat young and old objects differently, mimicking the efficiency of G1GC but with near-zero pause times.
4. Why You Shouldn’t Use All 64GB
At GameEngineer.net, we frequently see “Out of Memory” (OOM) crashes on 64GB systems because users set -Xmx64G.
- OS Overhead: Windows/Linux needs ~4GB for background tasks and networking.
- File System Cache: Minecraft benefits significantly from the OS using “Free RAM” to cache region files (
.mca). If you allocate 64GB to Java, the OS cannot cache these files, forcing slow Disk I/O. - Compressed OOPs: In Java, if you exceed 32GB, the JVM stops using “Compressed Ordinary Object Pointers,” which increases your memory footprint by up to $40\%$ while decreasing performance. Never exceed 31GB unless absolutely necessary.