Why is my fresh install of 12.04 running slow?
Your slowness may be due to the fact that you are using Intel HD Graphics. Linux does not have very good 3D graphics support for Intel Chips. Also, in 12.04, Compiz eats a lot of memory. Use a 64 bit Ubuntu with either Gnome 3 or Cinnamon desktop for graphics effects. They use less amount of memory than compiz. Or if you want, you can use Unity-2D, faster with no 3D effects. 32bit Ubuntu cannot use more than 2 GB of RAM. If you use 64 bit, Ubuntu will use 3.7GB of RAM