To level the playing field, I took the glibc quicksort implementation from http://sourceware.org/git/?p=glibc.git;a=blob_plain;f=stdlib/qsort.c;hb=HEAD http://s

To level the playing field, I took the glibc quicksort implementation from http://sourceware.org/git/?p=glibc.git;a=blob_plain;f=stdlib/qsort.c;hb=HEAD http://sourceware.org/git/?p=glibc.git;a=blob_plain;f=stdlib... (which is actually a hybrid algorithm), modified it to use a comparison function with signature _Bool(const void* , const void* ) as we're only interested in whether an element is less than another, and included the source code verbatim (which is essentially what including <algorithm> does). The C++ code still outperformed the C code, but the ratio dropped from ~2.8 to ~1.4. 40% performance gain is nothing to sneeze at, but it's far less impressive than the sensational 3x from the headline. The remaining difference is probably due to the choice of algorithm: the GNU STL algorithm is introsort. While it's also a hybrid algorithm based on quicksort, it adds heapsort to the mix, which is known to outperform quicksort on random data.