Xubuntu is a lighter version of Ubuntu that uses Xfce as the window manager. From the homepage: "Xfce is a lightweight desktop environment for various *NIX systems…"
Xfce is a lightweight desktop environment for UNIX-like operating systems. It aims to be fast and low on system resources, while still being visually appealing and user friendly.
Installation of XFCE on Ubuntu/Linux mint, open Terminal and enter command:
sudo apt-get install xubuntu-desktop