On Chrome, my sim runs at about 40 ticks/sec on my fancy macbook. Safari and Firefox only get 5-10 ticks/sec.
On an older core2duo HP laptop I see 15 ticks/sec for Chrome and 3-5 ticks/sec for Firefox, on both Linux and Windows.
A new cheap Asus laptop gets numbers very similar to the core2duo, but the rendering works a lot better due to better graphics card.
I want to move some priority queue code I have to handwritten asm.js when I get time, but don't expect it to make a big impact.
Its just so hard to actually profile your code and understand your bottlenecks. What happens in web workers is basically invisible.
Before I had web workers my putting sim ticks into the render callback was making the game very unresponsive, particularly in Firefox.
I dream of the game working on tablets etc, but that seems a long way off.
Games like the original simcity and tycoon series and a-train all worked well on really really low-end machines, at performance that seems out of reach for javascript games that basically work the same :(