[plt-scheme] Strange issue in getting DivaScheme prepared for 4.0: compilation time and memory is huge!

I just put up a new DivaScheme package up on PLaneT that should work
with PLT Scheme 4.0.

However, I'm seeing some strange issues with DrScheme compilation.  It
takes an unusual amount of time and memory to install DivaScheme on a
clean DrScheme 4.0, and I haven't been able to trace why.

Basically, if I have a virgin DrScheme 4.0 installation, I must
initially tell DrScheme to use at least 256MB of memory before
evaluating:

    (require (planet "install.ss" ("divascheme" "divascheme.plt" 1 4)))

If I instead keep the 128MB memory ceiling, compilation will fail
because it hits the memory ceiling.  (And what's also surprising to me
is how darn long it takes to compile.)  This is violating my
expectations on how expensive compilation is!  Does anyone know what's
going on?