GNOME can be easily optimized for Netbooks using configuration editor. Disabling animations, thumbnails and splash screen speeds up GNOME while scaling down icons saves space on desktop.
Metacity will give the user less feedback by using wireframes, avoiding animations, or other means if /apps/metacity/general/reduced_resources is set to true. This can be set with gconf-editor or from shell with gconftool:
gconftool-2 -s /apps/metacity/general/reduced_resources -t bool true