This topic described it all.
I understand the reasoning to avoid long stop the world GC. So reducing the RAM will shorten such event. But it would make old GC happen more often if the heap size is reduced.
From my experience, it's more troublesome to have old GC more frequent.
Is the issue of too much heap really just a function of GC algorithm? Meaning with G1GC, we don't really need to worry about it.