My AMD Server seemed to be running out of RAM this morning. Checking the processes, it appeared that Unity 3D was using approximately 18G/32G (i.e. with no virtual machines running, the OS was still using 18G). Why? I don’t know why Unity 3D freaked out, but ‘compiz’ was chewing up 1.5G all by itself. A quick check showed that Unity 2D is no longer available in Ubuntu 14.04.
So, I installed gnome-flashback-session.
After it was installed, and after the logout and login under Metacity, the baseline RAM footprint dropped to 1.5G total.