Personally, I am more interested in improvements to asm.js like code. The limitations of asm.js, in particular the inability to allocate memory, greatly limits its usefulness for many applications.
A work around is to pass a foreign function into your asm.js module to do allocations for you, but then you have to either implement your own GC, do reference counting, or just come up with some hand rolled lifetime management.
I'm also interested in how asm.js could be improved in this regard without moving away from its existing barebones model. Would love to hear ideas.
I think the first thing we will see is shared array buffers between workers because games really need that.
We're interested in that too; see the "Firefox (no asmjs)" line in those arewefastyet graphs. That shows Firefox with asm.js-specific optimization disabled.
"Performing well" in this case still means significantly slower than Firefox does on the same code:
http://arewefastyet.com/#machine=12&view=breakdown&suite=asm...
Which isn't to say that it's not a big improvement over where it was. But there's still a way to go on making it competitive, so far as I can see.
Edit: Got name of the original engine wrong.