Excel file with Active X programming growing uncontrollably
 

I have designed an Excel spreadsheet with a number of formulas, buttons
(Active X) and VB code connected to them. All it does is calculations on
values in cells and on other worksheets and workbooks.

I regularly save the latest version of this Excel file under a new name. But
every time I do this it seems to grow enormously. The first version was 734
KB. There are only minor changes in the program since then, but the latest
version has grown to 7,7 MB! But there is really no more data stored in it
that in the first one.

Does anyone have a clue what is happening here, and what I can do?

Thanks