Yes. Node.js supports only a single processor core. I don't know much about Meteor but it doesn't look like it offers concurrency features.
The concurrency in Go (and to a lesser extent in Node.js--probably) is amazingly performant. For example, when I poll & parse 100 RSS feeds and the slowest one takes 6 seconds to return from the remote site, the whole routine returns in < 7 seconds. A synchronous single-core app would take up to 6 seconds * 100 = 10 minutes for the same process. In Go, when I call out to the remote sites, each call returns immediately, so that all 100 remote calls finish immediately. Go puts my routine into a dormant state while waiting for the remote sites to return data. So during that 7 seconds my app may have ~5 seconds of dormancy to do other processing (in a completely independent code path), again using all the machine's cores.
The concurrency in Go (and to a lesser extent in Node.js--probably) is amazingly performant. For example, when I poll & parse 100 RSS feeds and the slowest one takes 6 seconds to return from the remote site, the whole routine returns in < 7 seconds. A synchronous single-core app would take up to 6 seconds * 100 = 10 minutes for the same process. In Go, when I call out to the remote sites, each call returns immediately, so that all 100 remote calls finish immediately. Go puts my routine into a dormant state while waiting for the remote sites to return data. So during that 7 seconds my app may have ~5 seconds of dormancy to do other processing (in a completely independent code path), again using all the machine's cores.