How to increase performance in EngageOne Server when File Partition Number is small

Software Affected: EngageOne Server
Product Feature: Batch (Non-Accumulated)
Partition size determines how many records are run for each file.

For example, if using an XML file with 1000 start of publications and set the file partition number to 5 it will take 5 Minutes and 14 seconds to process all the entries resulting in 200 PDF files.  If I take the same file an set the file partition number to 1001 it will take 19 seconds and will only produce one file.
UPDATED:  November 3, 2017