Single page apps are pretty ubiquitous these days. Most large web apps are single page apps (e.g. Facebook).
In general when building something you shouldn’t worry too much about performance for the start. Build your app and then optimise it when you find the performance bottlenecks. Meteor has been shown to have very good performance in production apps using only a small server.
I remember reading something about the game Dominus which is built using Meteor. It’s a pretty heavy app but apparently it still manages to run smoothly with 200 concurrent users on a single Modulus.io servo.