VMS Help FORTRAN, /OPTIMIZE  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  /[NO]OPTIMIZE=(option[,...])    D=/OPTIMIZE=(LEVEL=3)

  Selects compiler optimizations to be applied to the generated code.

  Specifying /OPTIMIZE without any options is the same as specifying
  /OPTIMIZE=(LEVEL=3) and is the default.  Specifying /NOOPTIMIZE is
  the same as /OPTIMIZE=(LEVEL=0).

  /NOOPTIMIZE (or LEVEL=0) cannot be specified if /VECTOR or
  /PARALLEL=AUTOMATIC is also specified.

  If /DEBUG is specified, Compaq recommends that /NOOPTIMIZE also be
  specified, if applicable, so that generated code is not rearranged
  which can make it more difficult to follow program execution in a
  debugging session.

  The compiler will issue an informational message recommending
  /NOOPTIMIZE if /DEBUG is used without the /NOOPTIMIZE qualifier.
  To disable this message, specify /OPTIMIZE explicitly.

  See your performance guide for information on optimizations
  performed by the Compaq Fortran 77 for OpenVMS VAX Systems compiler.

1 - LEVEL

  Controls the level of optimization performed by the compiler.

  LEVEL=0 is the same as /NOOPTIMIZE and suppresses all optional
  optimizations.

  LEVEL=3 is the default optimization level and provides all optional
  optimizations except memory blocking.

  LEVEL=4 provides all optimizations including memory blocking, which
  can improve performance for non-vectorized applications that
  operate on large arrays.  See the performance guide for more
  details.  LEVEL=4 cannot be specified if /CHECK=BOUNDS is in
  effect.