/FAST

 /FAST
 Sets the following qualifiers that usually improve run-time
 performance:  /ALIGNMENT=(NATURAL, SEQUENCE), /ARCHITECTURE=HOST,
 /ASSUME=NOACCURACY_SENSITIVE, /MATH_LIBRARY=FAST (Alpha only), 
 /OPTIMIZE=(TUNE=HOST) (Alpha only).

 The default is /NOFAST.

 If qualifier /STANDARD is specified, /FAST does not set
 /ALIGNMENT=(NATURAL, SEQUENCE).

 Note that programs compiled with HOST architecture and tuning
 optimizations may run slowly on systems with earlier generations of
 Alpha processors than the compiling host system.