Its because of the remaps of some items thats not in the game anymore, like old event items and such. Since those files is not ingame anymore, while cooking devkit includes all files related to those items and thus increased file size. I tried to clean up as much as I could but still missing some.

It's actually caused by the tek tier wall pieces being larger, maybe due to artwork(?), which seems unrelated to a stacking mod. Is this an accident?

http://i.imgur.com/kD9BlLn.png

http://i.imgur.com/rfm5gZk.png