Reorganize the Wiki
Giulio told me (Phil) that the wiki has been "flatten" (all pages merged in a single page).
The reason was to be able to export the whole documentation as a single file.
But, it makes editing more difficult, the structure less flexible and more difficult to nagivate, and as the documentation grows the single page becomes heavier and heavier.
I quickly checked and found that Redmine has an option to export all the pages in a wiki as a single document, which should address the initial concern.
See here: https://www.redmine.org/issues/3463. In short, one just needs to go to an index ("Index by title", on the right), then just click one of the option in "Also available in: " (PDF, HTML)
So i suggest that the wiki is re-organized with several, small pages.