If interwiki tags are used a lot on a page load (ex: listing of stories in a category) the number of database queries can add up quickly. On some pages we were seeing 200+ "SELECT iw_prefix, iw_url, iw_local, iw_rel from {interwiki}" queries. While these are simple queries if there are other taxing queries on the page it can still add sql load.

Per some guidelines here on using a static variable: http://www.lullabot.com/articles/a-beginners-guide-to-caching-data

We added a simple modification of the process function to use a static variable for a page load as any changes in the interwiki list should likely not be of concern for a single page load:

https://github.com/aadl/interwiki/commit/862e4de1faa5b7cbe0200bf62c22dd7...

There are probably cleaner / more drupal ways of doing this. Drupal 7 has a static function:

http://api.drupal.org/api/drupal/includes--bootstrap.inc/function/drupal...

We saw some pages have their number of queries halved. If someone wants to clean up the patch and integrate it please do.