The lazy loading feature will resolve this.

Start up time was reduced to around 300ms.

Note:
 My linux environment is on slow VMware, thus system calls and
 file I/O is very slow. So current result is not so bad.

I think that current lazy-loading based startup (r352 of new repository) is a
reasonable trade-off point.
To reduce the startup time more than current implementation, we should load all
necessary codes as one file of dumped lisp environment. We should migrate to
modern Scheme implementation before the trial.
It's a future issue.