There was some talk a while ago about this. I gave it a shot back then and it was a CPU-hog. With the latest strides in JavaScript (both browsers & the technology), it might be worth another look:
https://ancillary-proxy.atarimworker.io?url=https%3A%2F%2Fbespin.mozilla.com%2F
Can you compile Firefox & Ubuntu yourself and get better performance, then?
It has just been discovered that research causes cancer in rats.