What I need is performance, eye candy is optional.

My primary desktop environment is Xfce, as it is more lightweight than GNOME, KDE, or Cinnamon (Mate is out of my choice), yet it has more goodies (plugins) than LXDE. But due to my 4-year-old laptop, I found that LXDE has better performance than Xfce significantly. I can run multiple heavy applications at the same time, especially Firefox and Chromium. Xfce performance drops when I run both applications simultaneously. Switching between applications is slower. If running with Skype at the same time, and doing some development testing, the performance drops drastically.

As using Arch Linux, the advantage is I can choose any Desktop Environment or any Window Manager. Recently, I have tried several Desktop Environments and Window Managers which are officially supported in Arch Linux. After trying, I learnt the differences and similarities among these Desktop Environments and Window Managers.

Desktop Environment

My primary Desktop Environment is Xfce4. Previously was GNOME 2. Since the release of GNOME 3, I chose Xfce4 as it is more conventional and there a lot of useful goodies (plugins). It is also lighter than GNOME.