Well, I'm involved in a project that uses Deki Wiki, and it is slow.... slow.... slow. Navigating to another page takes some 8-10 secs, and opening up the editor on a page takes some 20 secs. Could be it's just the free Deki Wiki hosting service we're using (maybe the wik.is domain name is a bit of a give-away), but all I'm saying is: watch out.
A friend setup a similar instance; when I went in to make a trial edit, I didn't notice that. Perhaps it could be the host, perhaps not. Hard to tell. All in all, however, Deki Wiki, Drupal, Plone, and many of the rest of the LAMP-stack and similar (Deki Wiki is not LAMP) are pretty much cast in the mold of wiki/blog/forum/im as "solutions" when, to some degree, they contribute to the "problem" by not paying attention to granular addressability, navigability, and structure. We pretty much have the same problem here in Ning: there's no subject index anywhere, for starters. If someone does not happen to read this post, they will never have a chance to know that someone talked about granular addressability here, for instance.
It's possibly a case of cost/benefit tradeoff. Ning is providing a low startup effort, lightweight shelter for us to stay aware of each others' activity, in a decent interface that I'm happy to expose to the world for the moment. We need our own tools for deeper deliberation, but I'm happy to continue with it at present, focusing resources on making our own tools smarter and more interoperable. (If we switch, then I doubt we can migrate this content — which I realise is of course a very strong argument to switch sooner to a more open system, if it's usable and robust!)