Indesign to heavy file size

Some this have been already recommende but as a summary:

• "Save as" (this makes wonders, really)
• Delete any unused element you might have left in the canvas / working table (specially pictures).
• Delete any unneeded master page that might have 'heavy' elements
• Clean the XML Structure. It might be full of unused / duplicated elements. This one might be a forgotten real pain in the ass when it comes to absurd troubles.
  
  

Anyway Splitting into an InDesign Book document (indb) is best practice

Best regards

600 Mo (or megabyte) does not seem that high for a 300 pager to me. To speed things up see what happens if you go through View>Display Performance>Fast Display. By default the program should be showing "Typical Display" under Display Performance but if it is showing "High Quality" then, in that instance, try "Typical".

What about using the book function and split the document by chapters?

see here: https://www.bookdesignmadesimple.com/using-the-book-feature-in-indesign/

https://helpx.adobe.com/indesign/using/creating-book-files.html

Hi,

Can you confirm the version of InDesign and the Operating System you are using?

Can you try to save the file as a IDML file, open that in InDesign and make a SaveAs back to InDesign, this can help you purge a lot of unwanted Mo and keep what you need.