Why is memory footprint smaller when compiled static?

[Preben Randhol <randhol+abuse@pvv.org>]

I compiled my application (a GtkAda program) on Linux first as:

   gnatmake glosa -O3 `gtkada-config -static` -bargs -static

then as

   gnatmake glosa -O3 `gtkada-config`

I stripped both executables afterwards (as I forgot the -s flag)

The executable sizes becomes:

   2583572 bytes for the static version
    752060 bytes for the dynamic version

When I run the two programs and examine the memory usage of the two
programs I find :

   3296 kb for the static version
   4412 kb for the dynamic version

Why is there such a big difference? Is it because the compiler can do
better job at optimising the code when you build it statically.

I also did the same without the -O3 switch and then the memory usage
was:

   3412 kb for the static version
   4512 kb for the dynamic version


Preben who knows very little on how compilers work