Whenever I set up a VM with Ubuntu I want to fall back to a lighter desktop with fewer effects. Here's how to install the classic Gnome desktop and make the new Unity desktop optional on login.
Ref: http://www.howtogeek.com/189912/how-to-install-the-gnome-classic-desktop-in-ubuntu-14.04/
1) sudo apt-get update; sudo apt-get install gnome-session-fallback
2) Logout
3) Login with Metacity icon option
Happy days.
