I've done some work at converting the Wikipedia to Postgres, but am not there yet. So, let's put that aside for now.
It seems that the wiki "source" is "interpreted" into html every single time someone accesses a link. That seems like a lot of overhead.
Given that for every time a change is made to the wiki source to a page, several people "view" it, why not just regenerate the html only when changes are made, and store it? It would take more storage space, but should be MUCH faster. And if storage is an issue, I can donate some hard drives...
The savings on the Recent Changes page alone should work wonders.
Jonathan