Source : Free On-Line Dictionary of Computing

hand-hacking
     
        1. The practice of translating a {hot spot} of a program in a
        {HLL} into hand-tuned {assembly language}, as opposed to
        trying to coerce the {compiler} into generating better code.
        Both the term and the practice are becoming uncommon.
     
        See {tune}, {bum}, {by hand}; synonym with cruft.
     
        2. More generally, manual construction or patching of data
        sets that would normally be generated by a translation utility
        and interpreted by another program, and aren't really designed
        to be read or modified by humans.
     
        [{Jargon File}]
     
        (1995-02-16)