The referenced array is a part of animations displayed on some custom display. So, the more compressed this data is, more animation i can show.
I have done animation using the '51 and let me tell you that SPEED is the killer. I started out without any knowledge of the speed requirements and wrote the application in 'plain vanilla C' and it was a disaster. Now it is running fine in 80% assembler. I doubt very much that you will be able to (un)compress anything fast enough to achieve any acceptable animation.

Erik