Why are the alias so big in filesize in Mountain Lion? I noticed the alias(es) that I create in Mountain Lion are very big in filesize (for example an alias to a folder is 5.8MB!)

Compared to Leopard, they were just about 500KB.

Why is this? and is there a way in the system where I can make them smaller without resorting to creating alias via the terminal?
Since Lion, in addition to storing Retina icons, it seems that an alias stores its many different sizes of icons in both the data and the resource fork (the xattr com.apple.ResourceFork). Possibly in a move away from Resource forks, while still supporting previous OSes (for now).

The alias I just created contained the follow formats:
is32, s8mk, ic11, il32, l8mk, ic12, ic07, ic13, ic08, ic14, ic09, ic10

They are described here: http://en.wikipedia.org/wiki/Apple_Icon_Image_format