Many options are available to a programmer when attempting to optimize a code.
These can vary significantly in both difficulty and effectiveness. Fortunately, some of the easiest optimizations to apply also yield the biggest payoff. A good example is the replacement of a hand-coded linear algebra solver with a libsci, ESSL, IMSL, or other library routine. A related optimization that most users are not aware of is the use of vendor-supplied vector intrinsic routines. These vector routines have been optimized so as to make best use of the arithmetic functional units, thereby maximizing throughput.