I ran the applet on my Mac and its memory consumption on that ebook was 97MB.
I used -Xmx32m to cut it back to roughly the amount of heap available on the iLiad and it started acting much like it does on the iLiad.
With those Archive titles, with other DJVU titles it runs happily on 32MB.
At a guess the de-compressor used in the Archive ebooks needs a bit of optimization.