Personally I don't mind RAM usage that much. I'm more concerned about excessive CPU usage resulting in unnecessary battery drain on my laptop or annoying fan-spinning.
Atom for me consistently sits at 0-0.1% (mostly 0) CPU usage when idling. You may want to investigate some of the extensions you're using if the numbers are different for you.
It's probably not idle CPU usage that the parent is complaining about.
Yeah, this was more a generic comment not specifically aimed at Atom. Sorry if that wasn't clear.