how to break up a large module?

[David Roundy]

I recently spent a couple of hours breaking up a large module (2.5k lines)
into several smaller modules.  When I finally got it working, I found that
my program took about 60% longer to run.  This was running ghc with -O
optimization.

Any suggestions how to go about breaking up a module in such a way that it
doesn't slow things down? Do I just have to go adding INLINE directives to
all my functions? Or is there some other trick I could use?

For the moment I've reverted to my single big file method, but it certainly
would be handy to be able to break that up so that it wouldn't take so long
to recompile.
-- 
David Roundy
http://www.abridgegame.org