If I copy the source, those pages take about 7 seconds to load here. I suspect the parsing is slowed down dramatically by another modification you are using. What other mods are you using that affect the parser? Would it be possible for me to have a look at your plugin code to see if there is some inefficiency there?
As a side note, those pages are ridiculously long anyway, and should be reduced in the best interest of your server hardware. I recommend separating them into multiple pages, perhaps as part of a Book.