Salut LODR I think you wanted to say "80 megs ram and not gbs..."
Well to answer your question, normally on os x LW should use up to 100 megs RAM... but it seems that there are bugs in the latest java implementation by Apple. At least a bug fix version of java is coming so maybe LW on os x will use less RAM. See there for my source:
http://appleinsider.com/article.php?id=644
For LW on windows RAM usage and CPU cyles are pretty low. I never got more than 80 megs RAM used by LW under Win XP and java 1.5. I don't know the figures for Linux and FreeBSD though.
À la prochaine!