include files with :=

[Dill, John]

I am still trying to track down where exactly my lag time is coming from, and 
it doesn't appear to be from using the include directive by itself.  My 
question is how makefile evaluates variables that are defined using ':=' with 
respect to include files.

If I have a file include_me.mk which contains:

my_var:=$(shell script)

and I have included this file several times (indirectly through my file's 
dependent include files).  Does make re-evaluate this variable assignment each 
time 'include include_me.mk' appears?

If that's the case, then I think that's where my problem is.

Thanks,
John