b25987 - greatly reduced ISO size, what has been removed?

Hi everyone,

I have spotted that the ISO size has been reduced alot. Much appreciated!
Could we receive information, how these savings have been accomplished?

200 MBs are much considering the compression and dedup process of WIM.

core files: nearly no change
sources dir except WIM -3 MB
install.wim -200 MB

former release 25967

current release 25987