Jim Bernard <jbernard@mines.edu> writes:

>   My guess is that the two different execution times represent runs
> in which the program was loaded with different alignments of
> double-precision variables, one efficient and the other not.  I
> tried compiling with -malign-double, but that made no difference.
> I've tried a large number of variations in compile-time optimization
> flags, including no optimization, and nothing made much of a
> difference.

I doubt that would make any difference; your variables should be bound
to the same address in every run.  Try compiling your program with -pg
and see if gprof gives you any insight into where the extra time is
being spent.  That might be a good starting point.

Ben