Yes, as of Chat Mapper 1.3, we have added several options to lower the size of XML exports.

First, in the application preferences (menu option: Tools -> Preferences...), you can specify an option to disable the export of empty asset fields.  This typically results in a savings of about 50% with this option alone.

Second, there is also an application preference to disable export of asset field hints.  These hints are generally only used within the user interface and can usually be safely disabled.

Third, each asset field definition has a "do export" option that can be set on an field-by-field basis (menu option: Project -> Project Settings...).  If there are certain asset fields that you know will never be used outside of Chat Mapper, disable these for extra savings.

Lastly, as of Chat Mapper 1.5, we have added a new "XML Export with Options" exporter that allows you to exports all conversations to separate XML files, or to export only a single conversation.

Also, you may consider the use of our new JSON data exporter, which inherently produces much smaller file sizes and works well for web applications or Unity 3D.