That actually looks really promising.
The performance of the pokemon demo is really bad on Firefox unfortunately, but near perfect on chrome.
I would love to talk with someone understanding Spidermonkey's inners to optimize the code! Javascript optimizations are pretty hard since they can suffer huge variations across browsers.
Anyway, I also have a lot of work to do to achieve Grantgalitz' performances even in Chrome, so it should improve over the time :)