I've changed my OP to include a link to the latest version of the examples in the reactive programming presentation. I can already see that the method .unchanged has been renamed to .stable since the PDF was generated so you'll definitely need to refer to the repo. The latest code should work with both the MoarVM and JVM backends bundled with Star.

We've recently reached the point where there's the first microbenchmark that runs faster in P6 than P5. But in general it's still early days for Rakudo/NQP/MoarVM optimization. If you expect Rakudo Perl 6 to be extremely slow then you can't be disappointed and you might even be pleasantly surprised. :)

If you end up trying Rakudo I strongly recommend you visit the freenode IRC channel #perl6.