Actually the hack that dont_use_nlink disables only speeds up the most basic find operations where you don't care anything about the files to be found and then don't do anything with them. And it breaks File::Find on every platform I've ever used it on, just not on every file system on every platform.
The default should be made to not use this bad hack on any platform. The days of "most file systems of most Unix systems" supporting this hack have long since passed (it has been a long time since I've seen a Unix system without a CD-ROM drive, just to pick one example).
Sure, it was a cool hack a long time ago. And it can make just getting a listing of files much, much faster (depending on how your directories are structured). But a good module should err on the side of giving correct results over performance.
(but my friends call me "Tye")