[jlongster]

Thanks. I'm not sure about setTimeout, I can't imagine it's slow, but it might be something with context switching.

There's probably things you could do in the VM to optimize performance for Firefox. If you developed the VM in Chrome, typically people optimize for it Chrome. I can usually get relatively close performance if I tweak a few things here and there for both Firefox and Chrome.

Although, I think Firefox's main performance comes from JIT-ing, which you've totally lost if your running in a VM. The above example is a loop, which would usually perform great, but you've lost the JIT. That may be a reason.