Since vanilla minecraft
If you play in the same world for a long time
Starts using 3 gigabytes of RAM out of 6 available
Then he starts to eat up all the back memory, rarely deleting it up to 1 gigabyte
For example, if you are tired of playing in one game
If you go to the server, it still eats up 3 gigabytes
That is, the game does not clear the base memory when re-entering another world or server

I suggest that the mod clear the memory when entering the server or another world
Thus, it will be possible to play without restarting minecraft

How are you measuring memory usage here? Are you looking at the task manager/htop/etc or at the memory usage on the F3 screen? The first one is virtually impossible to control from within Java (the JVM tends to use as much as you allow it to use), FerriteCore only tries to improve the second one (heap size).