* Don't render blog archive pages unless a page is added/removed. Just
  changing a page doesn't affect the archives as they show only the title.

* Look at splitting up CGI.pm. But note that too much splitting can slow
  perl down.

* The backlinks code turns out to scale badly to wikis with thousands of
  pages. The code is O(N^2)! It's called for each page, and it loops
  through all the pages to find backlinks.

  Need to find a way to calculate and cache all the backlinks in one pass,
  which could be done in at worst O(N), and possibly less (if they're
  stored in the index, it could be constant time). But to do this, there
  would need to be a way to invalidate or update the cache in these
  situations:

  - A page is added. Note that this can change a backlink to point to 
    the new page instead of the page it pointed to before.
  - A page is deleted. This can also change backlinks that pointed to that
    page.
  - A page is modified. Links added/removed.