haruspex: Hence my comment above that line,
If your program makes heavy use of a sorting routine, you may want to consider implementing a tailored sort function rather than just using qsort().
By no means do I suggest writing your own low-level routines for no reason... but if your program is spending a lot of time sorting, then you might consider writing a tailored sort routine. Obviously this wouldn't make sense if sorting is barely even on the radar as far as time spent in your program.
Hopefully this clarifies my position and the intent of my wording (which I admit may have been unclear).
Note, also, that all of my entries in my blog series on sorting start off with an unoptimized version of the sort routine, implementing them as closely to the description of the algorithm as I can. From there, in each entry, I went on to describe my mode of thinking on how to achieve better performance (largely as an educational challenge to myself) - e.g. I never suggest pre-optimizing.
Update: more on sorting here.