mongodb/mongo-perl-driver — pull request #56 by SailingYYC (2013-01-19 00:05:32+00:00)
Title: MongoDB::Cursor::hint() requires ordered hashes.

+1 - Currently a performance impacting issue.

Hash order is important, otherwise the driver reports as a "bad hint" as order is not maintained.

I believe there are other issues underlying this. In the MongoDB shell, executing a sampe query with the hint runs 4 times faster than without, but running it through the perl driver there is no speed increase (290ms with hint vs. 1343ms w/o hint - averaged over 100 requests).