I have a webform written in C# in Visual Studio 2022 17.1.3. This webform has multiple pages that produce PDFs using iTextSharp 5.5.13.3 and the code used to generate each PDF is housed in an App_Code helper class. Up until recently, these PDFs had relatively small file sizes, usually < 300 KB. However, the newest page is producing PDFs that are over 1,000 KB, regardless of the content.
The PDF class is called from a ListView's ItemCommand, which is how all of the other pages call their PDFs. The code for this page was copy/pasted from a previous page that does not have the file size issue.
I have tried copy/pasting the PDF generating code from a working PDF into this new class, I have removed all of the generating code entirely and just had it print the word "test", I even changed the ItemCommand so that it called up a working PDF that I know is smaller, none of them seemed to impact the file size in any meaningful way.
Using Acrobat's Audit Space Usage I discovered that the Document Overhead on the broken PDF is taking up 99% of the file size, around 1,255,000 bytes for the "test" document, and that smaller PDFs have a Document Overhead around 4,000 bytes. Audit Space Usage Test
Does anyone know how to reduce Document Overhead, or what could possibly be causing this much bloat?
EDIT 1:
If I open the PDF in Acrobat and re-save it, the file size does shrink, I guess Acrobat auto-optimizes the file then. Here is the updated Audit Space Usage of the test PDF
Audit Space Usage Test after save
EDIT 2:
I have made a discovery. The main difference between this page and the previous pages is that this page also has connections to SharePoint using an ObjectDataSource. I return a list of documents and display them in a ListView that uses the ObjectDataSource with DataSourceID. Both the Document ListView and the ODS are in a separate UpdatePanel from the PDF button. I removed DataSourceID from the ListView and instead set the DataSource in the backend and that fixed the PDF file size and I have NO idea why...
Why would an ObjectDataSource connecting to SharePoint impact the file size of an unrelated PDF being generated by the page?
Why would setting the ListView's DataSourceID in the front end impact the file size but removing that and setting the DataSource in the back end fix it?
Here is the audit from the new file:
