Advise Needed! Question on Memory Usage.

[RealMichaelDino]

Hello hello!
Awesome mod you got going here! I am currently planning to add this and its addons like Clockwork and Eureka to my personal modpack for playing with a couple of friends. However, I notice whenever this mod is enabled it tends to require quite a lot of resources, and I've heard from some places that the physics engine uses memory outside of the memory dedicated to minecraft???
I'm not sure if the latter fact is true but if so how much memory should I be leaving open for it to use, is there a general number or is it more variable on stuff like how many blocks there are added by other mods or if there are known mods to take up lots of resources when coupled with it etc.
Any advise and guidance is appreciated and if needed I can provide a general list of mods used in my modpack to provide some more insight.
Thanks for the help!

[Rubydesic]

About 2GB is generally good and the amount of off heap memory used depends on the amount of chunks loaded on the server