I’ve got a TTF font with about 50,000 characters in it. The font’s file size is about 20 MB. Some characters in the font are “composed” and reuse glyphs from other characters, for example  reuses the contour of the regular capital letter A, and if I make any edits to A,  is changed automatically.
In my FontCreator Professional Edition, what I’m trying to do is to make all the characters independent from each other so that editing one character doesn’t influence any other characters. FontCreator seems to have two ways of doing it and to my shame I don’t know the difference between them. First is to go to Tools menu > Glyph Transformer and add Decompose to the list of operations to be run on the characters. The second way which, according to my tests, similarly stops changes from propagation on other characters is to select all the characters and choose Make Simple in the Edit menu.
From what I’ve experienced, both of the ways result in the same number and appearance of the characters but the not in the same file size. The first way (adding Decompose to the list of operations) reduces the file size to 10 MB! That’s awesome news, but I don’t see how could this happen. If each of the characters becomes on its own and uses only its own glyphs, the amount of information the file should have increased. However, that’s exactly the output of the second way (Make Simple in the Edit menu), the file size increases by a megabyte or so.
Please help me shed some light on this paradox (or on my lack of knowledge). I’ve been searching through the FontCreator’s Help for a long time, and couldn’t find the answer (the info on the Glyph Transformer tools seems to be simply omitted there).