V8 is indeed very fast. There's plenty of data on that (assuming I wasn't being lied to for years, from multiple different sources :D).
The thing about Node is that is was build for handling every blocking action asynchronously by default. This doesn't make it faster, but it increases the concurrency (meaning more clients using the system at the same time).
You can achieve the same async pattern with other languages like python, even faster maybe. But it's not like "enforced" in the language's culture, you know? Django, for instance, which is one of the big python frameworks, won't do this out-of-the-box.
At the end of the day, it doesn't make thaaat much of a difference. Scaling applications horizontally is quite easy. In the real world, the REAL PROBLEM is your database. Trust me, if you want to build something that scales, worry less about your language and worry more about how you're accessing your data.