As I am mirroring a website now, there is something that puzzles me. The size
of the (root) folder (which contains many folders within it) was 2.7G and then
minutes later, it was 2.6G. Why the decrease in size?
However, the number of files and folders have increased.

I got this information by right clicking the (root) folder on 'properties'.
I'm on Windows 7.