It would be fairly convenient to be able to search the history of an article for the first occurance of a specific phrase. So if I want to know who inserted claim X into the article, I would just enter "XYZ" in the search box, and the next screen would show me either "no results" or the diff of the edit that added XYZ to the article, as well as the user name.

I don't think performance would be much of an issue, since article histories are very much limited in size. Site-wide search is so slow because our database is so huge. Histories could be searched by starting with the oldest revision, loading each one into memory and grabbing for a specific string -- don't know if this would be faster than an optimized SQL query. In any case, not much more than 10 revisions or so would have to be typically searched, with an average article size of 1000 bytes or so, and the feature would be fairly obscurely placed on the history page only. So I don't think it would add much load, but save us a lot of time otherwise spent comparing revision pairs.

Regards,

Erik