Adobe Freezing Issue for Basic Operations

We are investigating a significant performance issue in our Acrobat plug-in when processing very large PDF documents, particularly files in the range of approximately 7,000 to 25,000 pages. Without our plugin also adobe takes significant amount of time for saving pdf and deleting pages.

The plug-in performs basic document-editing operations, but these actions take an unexpectedly long time. During processing, Acrobat may appear to be unresponsive or frozen. The issue affects workflows such as:

Adding a symbol/annotation
Deleting a page
Saving the document
Using Save As
Our initial root-cause analysis shows that the majority of execution time is spent in the following Acrobat SDK APIs called by the plug-in:

PDPageAddNewAnnot / PDPageAddAnnot — while creating and adding annotations
PDDocSave — during document save operations
PDDocDeletePages — while deleting pages
We would appreciate guidance on the following technical questions:

Are there known scalability limitations or performance concerns for plug-ins using these APIs with PDFs containing tens of thousands of pages?
Are there recommended SDK flags, Acrobat preferences, save parameters, or plug-in design patterns that can improve performance for these operations?
When a plug-in calls PDPageAddNewAnnot, PDPageAddAnnot, PDDocDeletePages, or PDDocSave, does Acrobat perform full-document processing such as page-tree traversal, document validation, cross-reference reconstruction, object cleanup, or annotation/form-field updates?

Our goal is to make basic plug-in-driven editing operations usable for very large documents and avoid long periods where Acrobat appears to hang.

Any recommendations, known limitations, or best practices for Acrobat plug-ins working with PDFs of this scale would be greatly appreciated.