Beginning with Spotfire 7.5, saved analysis files are about twice the size of previous versions, and can be opened in the next-most-recent version.

Beginning with Spotfire 7.5, saved analysis files are about twice the size of previous versions, and can be opened in the next-most-recent version.

The size of the saved DXP file is about twice the size in version 7.5 as it was in previous versions.

For example: 
Spotfire 6.5
Size: 69.0 KB

Spotfire 7.0
Size: 80.0 KB

Spotfire 7.5
Size: 157 KB

 

 

Starting from version 7.5, you can now save an analysis in version 7.5 and open the file in one previous version (7.0.x).  Spotfire needs to save the file for compatibility to 7.5 and 7.0.x. This causes the files to be larger than normal. 

If you are worried about space and do not want this feature, there is an option to turn off the compatibility feature.

1). Log into Spotfire as an Administrator.
2). Click Tools, Administration Manager.
3). Select the “Preferences” tab.
4). Highlight the Spotfire user group whose Preferences you wish to edit.
5). In the “Preferences” sub-tab on the right, select Application, then select ApplicationPreferences.
6). Change the value of the SaveCompatibilityVersion preference to False.

After you log out, then log in as a user whose SaveCompatibilityVersion preference has been set to False, you can save the analysis file. The DXP file will have a smaller size, and opening it will require the current Spotfire version (or a newer version).
  Note: With the LTS and Mainstream offering, any files that are created in the latest mainstream version (Ex: 10.2) can be opened in the previous mainstream release (i.e 10.1) and the current LTS version , which is 7.11.x

Refer to the 'Compatibility Versions' section in the 'Spotfire Analyst Release Notes' as this section provides detailed information about the compatibility aspects:
https://docs.tibco.com/pub/sfire-analyst/10.2.0/TIB_sfire-analyst_10.2.0_relnotes.pdf?id=0