I profiled startup time a bit last year and much of it was in the
parser and malloc; so having this should be a win.

I've pondered having something like a self-managing cache in $HOME.  It
would be similar to what ccache uses for caching gcc output, but for
Ruby iseqs.  I've used ccache for over a decade it's never failed me.

Since 2.2 fixed iseq dumping/loading, we're closer to being able to
support this.  We'll need to be careful and correctly invalidate the
cache on any internal ABI changes, of course, and I don't want us to be
stuck on an old/stable ABI for a cache.

I don't think this will make distributing most Ruby apps any easier
(because C extensions are usually the biggest problem)