As I reported yesterday, the Bugzilla wikimo extension had to be temporarily disabled as it was affecting the reliability and availability of Bugzilla and wikimo. While the extension has query caching built in, we discovered that caching was disabled on the production wikimo cluster. This resulted in a very significant query load being placed on Bugzilla. The cache has now been enabled and the Bugzilla wikimo (mediawiki-bugzilla) extension has been reenabled. We are following up on some further performance improvements that should further reduce the impact on Bugzilla. You can help keep the Bugzilla load down by avoiding overly broad queries (like querying for all bugs) that you expect to return very large bug sets.
Thank you too everyone who provided their expertise in bug 731672 in order to get this extension back online quickly.