Marek747,
All languages have their ups and downs. "Language X is better than language Y" is just about as far from valid argument as you can get.
For an example, if speed is your first goal and popularity second, it would make most sense to forget node.js, RoR, and any given framework for that matter (they always add some extra overhead) and go with plain C instead (although that's just about as "old-school" as you can get). C is widely acknowledged as one of the most popular programming languages (TIOBE, IEEE Spectrum, etc.) and it's definitely the go-to language if you want superior speed.
That being said, web applications built on top of C are (to my best knowledge) very rare, and some developers would argue that it's not exactly an easy language to master. Just for comparison, something like Ruby (and Ruby on Rails, which is a framework you mentioned) is designed from a very different point of view: it was originally known to be very "hip", very comfortable to work with.. and extremely slow.
(I'm assuming they've improved those figures since then – that was quite a while ago – but Ruby is still hardly your best choice if you need top notch performance.)
If you want a language that's comfortable to work with, good for web application development (I'm assuming that's why you're here), and widely supported, go with PHP or Python. PHP is more widely used, which makes it a good choice. It's also ugly, inconsistent, etc. but a lot of developers have learned to live with those flaws because it's good at what really matters: getting shit done.
Note: I'm not saying that JavaScript and/or node.js is a bad choice, but they're not quite as popular or well-established yet, and the future of the web is bloody hard to predict. It's definitely good to have knowledge of them, but in my opinion they're not quite there yet. Perhaps one day they'll power all the popular apps around, or perhaps they're a fading trend, nobody really knows.