If the minifcation involves symbol substitution, the substitutions are going to depend on the content of the whole file. So unless you re-implement the minific

If the minifcation involves symbol substitution, the substitutions are going to depend on the content of the whole file. So unless you re-implement the minification algorithm to be optimised for minimising diffs you might find that every variable's name has changed and size of the file diff might start to approach (or exceed) the size of the file itself.