I've just posted a question on StackOverflow and thought I'd give a heads-up in here. Feel free to answer on StackOverflow for some rep. :)
http://stackoverflow.com/questions/11417390/how-to-improve-docx4j-performance-and-memory-usage-with-large-template-and-numer
We're developing an Eclipse application that allows exporting large EMF models to Word format using docx4j. The data can contain many rendered graphs in PNG format, and the Word template can be pretty large, with multiple repeat and conditional sections ...