Ouch !
If you are inclined you could try the amazon's
Kindlegen Gadget
Or... if you open an EPUB in the
Kindle Previewer then it will create the Mobi for you
But I have no idea if they will be any faster, the previewer is written in Java, yet another interpreted language - Yacc.
Problem with long running jobs is that Sods Law is always looking for an opportunity to strike.
BR