These file formats are remarkably compact, and so work well on the web. Experimentation shows that they can be decoded quickly in Java.
I experimented with decoding, scaling, and colorizing pk fonts into a gif image, and with rendering an entire page ahead of time, but found that this required more bandwidth and made links and other extensions difficult to implement. It also would have made the magnifier window difficult to implement.
The one page dvi files which are produced refer to each other by their dvi file names; the viewer software figures out which html page should be loaded to traverse a link. These files also retain their original psfile= specials; the viewer software figures out which gif file should be loaded to display the image.
This improves testability, since dvitype can be used to debug the new dvi files, and xdvi can be used for comparison against the display applet.