I don't have a stripped binary to compare with your numbers. I do see
a similar decrease in the size of the un-stripped emacs.exe, but I
cannot find any explanation for that. The size of temacs.exe is
almost identical between the 2 versions, which seems to point to Lisp,
or to data structures built by Emacs during loadup/dump process.
However, loadup.el saw no changes between the 2 versions, and
loaddefs.el is identical modulo time stamps of the files it records.
And I cannot spot anything pertinent, neither in src/ChangeLog nor in
lisp/ChangeLog.