Modpack configuration - Leiriad/-Neoforge-1.20.1-Inventorium GitHub Wiki
Inventorium is a heavy modpack, even with it's long list of optimisation mods, it still needs at least 6 GB of allocated RAM to work.
To configurate it, you'll need to go on your Modrinth profile and to click on "options".
Here, you'll need to check "override global memory", and to use the slider to choose an appropriate value for your allocated RAM, given your computer's specifications.
As an exemple, you can only allocate 6 144 Mb if you have a 8 GB system for you must keep some room to execute others programs than Minecraft in the background. If you have a high spec computer, allocating too much RAM is not recommanded. It is said that Java can badly behave when given too much space (see reddit discussion here).
OPTIONAL
On low end computers, Java Arguments can be used to optimize Minecraft's performances. If you want to experiment with this, you can by checking "override Java Arguments" above the Java RAM allocation section. You can find a few exemples of what you can do with a simple google/reddit search.
As an exemple, here are the ones I used to test the modpack at 6 GB RAM without shaders:
-XX:+UseG1GC -XX:+ParallelRefProcEnabled -XX:+AlwaysPreTouch -XX:+UnlockExperimentalVMOptions -XX:G1NewSizePercent=30 -XX:G1MaxNewSizePercent=40 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=200 -XX:G1HeapRegionSize=8M