Chrome is currently slower, but the v8 team is working on a new optimizing compiler called TurboFan. There are indications in the source code that it detects as

Chrome is currently slower, but the v8 team is working on a new optimizing compiler called TurboFan. There are indications in the source code that it detects asm.js code as a compiler hint of some form, hopefully this means it will eventually get quite fast on that type of content.