Fluctuation between 200+ fps to bellow 40 fps within seconds. No apparent cause.

Information:

Java: 18.0.1.1 64-bit
JVM args:
-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

(I got them from a closed issue, have tried without)

-Xmx8064 -Xms3072m

Forge version tested:

40.1.51
40.1.41
40.1.31
40.1.0

Hardware:

Processor: AMD Ryzen 9 5950X
Graphics card: NVIDIA GeForce RTX 3090
Driver Version: 30.0.15.1295
Memory: 32GB DDR4 (No OC)

I'm attempting to install Rubidium to see if that helps.

Rubidium crashes it.

Update: It does not, crash it, I had the wrong forge version. Does help, but still lower than expected performance. Its now more stable, fluctuating between 120-160 fps. Still way under the expected performance for my hardware, even when compared to other large modpacks. GPU usage bellow 35% consistently, and my spike up to 45%. CPU is <15%.

Try adding Rubidium Extras for other bugfixes/optimisations. Consider switching to Java 17 optimised JVM args that make use of newer GCs, e.g.
-XX:+UnlockExperimentalVMOptions -XX:+UseZGC -XX:+ZProactive -XX:ZCollectionInterval=600 -XX:+UseLargePages -XX:+DisableExplicitGC -XX:+AlwaysPreTouch -XX:+ParallelRefProcEnabled -XX:+PerfDisableSharedMem

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.