Media codecs are a microcosm of routines that want more care and attention than compilers are yet able to give. Some of RAD's decompression kernels are written in assembly, for instance, and a particular unicode transcoding routine was 20% faster in assembly than in c with intrinsics. An anecdote I heard: it was appreciably faster to run the linux version of postgresql in a translation layer under solaris than to run the native version, because the linux c library's strings functions were written in assembly. A particular binary search routine I rewrote in assembly (from c) was about 4x faster; I would estimate that about half of that was from an improved algorithm, and the other half was from the choice of language. (Of course, somebody else later made a c implementation that was a bit faster, owing to an algorithmic improvement...)