I've noticed for the past few projects that all of my indesign files are saving much larger than they should be. A file that started off as 30 MB will turn into over 200 MB with the addition of a few linked photos, text edits, and page layout reformatting. None of the photos are large enough to attribute to the exponential growth in file size.
For example I have a 20 page indesign file that has nothing but tables, text, and maybe 5-10 images. Today the file started off at over 100 MB, which is still huge, and by the time I finished editing with no additional photo edits or major layout changes, the file was over 300 MB.
I have tried resaving the file many times with the 'Save As' option, changed the save preview images to 'First 2 Page, small 128x128' and all of my photos are linked not placed. No matter what, it seems anytime a file is opened and edited it will almost double in size with no way to shrink it. Any ideas as to what is happening?
Import and export
Sync and storage
ID, like most apps of this general kind, adds and stores a bunch of working information to each file. Undo, image previews, etc. are added by default.
Even though your images are linked, ID stores previews of them. If they are particularly large files (for 300dpi print, for example), those previews are going to be large.
Save As will sometimes purge excess, but only until the next save, in which case all that working data is generated and stored again.
However, export to IDML and reopening that file (and saving again as INDD) will often purge more persistent junk data as well as fix small issues of corruption. You might try that, being sure to preserve your original file in case the translation loop loses something.
All that said, it does sound as if your base file is very large for the content. I have whole book files with many images that are only in the 15-25MB range before any save bloat. I do have book chapter files with embedded images that reach 50-100MB, though.
— | Word & InDesign to Kindle & EPUB: a Pro Guide (Amazon)