>> And, GC is a little bit slower. But, I think it's in acceptable range.
>
> Maybe you could/should make GC collector type user specifiable, to
> avoid the slowdown [this is what REE does I think].
> For instance on windows you don't need it.

I disagree. all of 'selectability' is just work around. Almost people don't
know GC internal so much. thus, they can't choose right gc so easily.
The right way is, many developers run his new gc and join his optimization
work. We definitely need only one fastest gc.