The applications can be shrunk by about 30 - 40 kb by using a PNG optimizer, pngout or Optipng.
Pngout seems to do well but you will need drag and drop onto the executable file by file.
You can use FileMenu Tools and set the Multiple Instances to sequential so that you don't need to drag and drop 40 or more files.
website of pngout: http://advsys.net/ken/util/pngout.htm