Firefox engine speeds past Chrome after Jager shot
Mozilla claims (a) SunSpider crown
Director of community development Asa Dotzler made the claim  on Monday morning with a blog post.
Mozilla tracks its latest benchmark numbers for its revamped engine here :
With Firefox 4 — now in beta — TraceMonkey will still look to convert loops, but when it can't, JaegerMonkey will convert entire methods into assembly. This new method JIT compiler uses the Nitro assembler from Apple’s open source WebKit project, the same assembler used by Google Chrome and Apple Safari. ®