A map that is 350kb will after a shadowcomputing and saving by a different name grow to aprox 1,3 mb.
Even when reducing the lighting and coppersize (removing blocks), the map will still be 1,x mb.
this problem seems to be present only after this latest patch. (b1,2E)
ie. this makes normalsize maps unplayable because of the 1mb limit.

EDIT: Even just resaving a map without doing anything to it does the bug

Well yesterday (with update B1.2e) I have recalculated shadows on a 500kb map and saved it with a different name and its still 500kb (both high quality).