Originally Posted by zeebra
If you want to run a cheap system that takes less power, then there are significant "performance gains" to be made from lowering the memory footprint.
If you want to run ancient machines with small amounts of RAM, yeah.
For newer machines, which tend to be more energy efficient than older systems, using a minimal system with a lower memory use desktop wont help that much.
If you've got 2GB+, the difference between the memory consumption of KDE 4.X/Gnome 3/Unity and really light desktops doesnt matter much, if at all.