You'd be right to be terrified, it's not exactly zippy. It's a toy, but I'm releasing it because it's got a couple of nice features (friendly REPL, lazy evaluation) and it's more complete in some areas than other toy Schemes I've tried. Also I figured it might be a nice example implementation for people who know Ruby. If you have optimisation suggestions or links to stuff I should read on the subject I'd be delighted.