Gentoo and Xine dev (and part-time "Amarok Helper") Diego wrote an
interesting blog about memory usage. Or, at least interesting to folks like me who somewhat regret never having had a operating systems class. He discovered that any Xine client (which includes Dragon Player or any KDE4 app that makes a sound) wastes 1.7mb of RAM thanks to libvorbisenc.
Using his cowstats script, I profiled Dragon Player: