gfortran produces huge executables

I'm new to Fortran (typically use Java and C++).   I'm have compiled
some F90 molecular dynamics code that has been passed down.  gfortran
produces huge (700 megabyte) executable files, while a trial version
of ifort produces an executable file under 1 meg.  The executable runs
in either case, but the large file size and compile+link times are a
nuisance. The large executable is likely related to a single large
object file, which is associated with a source file that defines a
large dynamically allocated (I believe) array.  Maybe this is some
flag that I have failed to set?

gfortran version: GNU Fortran (GCC) 4.3.0 20070810 (experimental)
OS: Intel OS X 10.5.2
Processor: 2.16 GHz Intel Core 2 Duo