InDesign file size saving extremely large

Let's assume the Photoshop files are not unnecessarily large because the are overgrown with document ancestors (as the above link to a script helps).

Get in the habit of planning in advance how large your PSD pix will be on the page in InDesign. Know how many inches/picas wide and tall and at how many pixels per inch you need them to be. Most prepress traditionally still asks for 300ppi at so many units wide and so many measure units tall.

Build to that size while editing in Photoshop. Visit Image > Image Size as well as Image > Canvas Size.

Make sure you understand that it is so many ppi at so many wide and so many tall.

Then place that carefully made image into InDesign using File > Place.

Done this way, InDesign does not build gigantic screen previews. The image doesn't need to scale down after placement either.

This has a dramatic impact on not having the InDesign file swell up in size.

The opposite situation causes InDesign to balloon with each pix placement:

Leaving the native file at 72ppi. Then...

File > Placing it by simply clicking and the pix comes out way too large and then you scale it down. Oof! Weight gain!

I had the same issue with a file that I got from a client. The Indesign file was 400 MB and the file would reach 900 MB very quickly. I had to do a Save as couple of times a day to bring the file size to the lowest size possible (around 400 MB).

I found that, the issue was with the PSD files linked to in the document, it seemed these PSDs had some non-image data that was read and stored in the Indesign file.

Luckily my file had only 2 PSD links that were used in 2 pages. I tried to revmove the hidden layers and any unecessary layers and save as the PSDs to new files, but still that didn't help my Indesgin file size much.

But it only helped when I opened the PSD files, selected all the layers in the file, including the hidden layers and duplicated them to a new file (right click + Duplicte Layer, destination New Document),  saved the new file and relinked to it in Indesign, then I Saved as a new Indesign file, my new file went to only 2 MB.

I suggest you check your PSD files, it might be one or more of these PSDs creating this issue with huge Indesign file sizes.

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.