How to reduce load time

[PATTON, BILLY \(SBCSI\)]

I have a makefile that includes 500+ other makefiles.  These files have
over 50k+ lines that are lists.
I also have 8 independent flows within the makefile.  Some depend on
others. 

I have 170 foreach loops in my Makefile and create 72674 targets and
still am not finished.  I'll probably add another 12k targets. It takes
a long time just to load and not execute anything.

If on the command line the user has to put
gmake build

Is there a way that I can do an if statement to avoid generating all the
targets by looking at the command line?

something on the line of
ifeq ($(findstring build,$(MAKEFLAGS)) , build)
-include make.build
endif