PSP as a PDF & other Document Reader

In addition to playing games, listening to mp3 collection, seeing photos, and being able to play many video format files, I wonder how to read my pdf files using my lovely PSP. Then I found this application, Bookr as a document reader. Version 0.8.1 supports plain text, PDF, CHM, HTML and DJVU files.
It works well for standard text-based PDFs but still hard to load more than 10 MB size pdf with pictures.
I downloaded from http://dl.qj.net/psp/homebrew-applications/bookr-v81.html, then to install I simply copy the Bookr folder to my Memory Stick PSP GAME folder.

Figures below are screenshot of Bookr running on my PSP :