Can't be done. Unless you intend to build your own super fast vm.

On my box Perl consistently runs in around 2 seconds, Ruby takes 9.

There is nothing that can be done to the source (other than getting  
the code to actually compile - your source is broken) that can improve  
more than a second or so on that performance.

Haven't tried it under JRuby though, you might experience better  
performance there.

But to honest I wouldn't sweat it that Ruby is not the best tool for  
this sort of thing (number crunching), my wife's car cannot best a  
dragster but it gets her where she needs to be.