Fastest JavaScript Runtime for RoR?

Question

Are there any known performance differences between the various versions of javascript available for Rails, such as therubyracer (maybe not the fastest), v8, node.js, etc., and if so, which can be considered one of the fastest of many?

Edit: Also, for most practical purposes and goals, how many real options actually exist? On further reading, everything seems to point to v8 ..

Answer 1

This post offers node.js as therubyracer code size was problematic. The documentation mentions node.js or therubyracer and nothing else, so I'm not sure what else is there.