java needs around 50% -75% more initial ram in linux than on windows.
the mem usage you see is
java+jd+heap
heap is only freed if not needed by jd and needed by os (means your os memory must be FULL in order that java will free unneeded memory), else heap will get freed very slowly.
its okay on linux that jd needs around 100-150mb on init.
you can change this alot by tweaking with java options and its garbage collector but that depends heavily on os, system, java version and so on.
my eclipse needs around 900 mb
