Ubuntu ships with Unity which was OK until I installed LXDE (Lightweight X11 Desktop Environment) using the following command
sudo apt-get install lxde
Although LXDE is a bit rough, it's way faster than Unity or GNome. On the same Notebook Unity took ~232 MB, while LXDE took ~140 MB of RAM. With a 4 GB RAM Notebook, a 72 MB saving of RAM won't make much of a difference. But, the snappiness of it makes me love and stick to LXDE.
LXDE site also claims that it requires less energy to perform tasks to other systems on the market, so I would be able to run on the battery for more time which is another plus. Noticed that LXDE boots ~ 20-25 seconds faster than Unity.
When Ubuntu introduced Unity, it took some time to get used to it, same is the case with LXDE also.
Thanks to howtogeek for the tip and the instructions.