[plt-scheme] Slow "require"

Hello,
 Why is mzscheme's "require" command noticably slow?
I'm not (only) talking about libraries from Planet; it's slow even for
local libraries from the default distribution.

For example, something like:
 (require (lib "1" "srfi"))
takes visible time. This slows down development (not everyone likes to
use long REPL sessions with EMACS... or EMACS for that matter), and
makes script usage not feasible.

This is not an issue for many other interpreters or programming
languages (for example, python's "import" command is for all intents
and purposes instantaneous).

(Btw: mred script running startup time is also really slow, even for the
simplest "hello world" GUI apps. Is this related?)

Regards,
 Mate