It's common sense once someone explains it to you, but when you're learning about all of this new client-side tech you tend not to worry about speed until later, and then it's useful to see posts like these telling you what you can do.
I guess this is why frameworks like Rails compile your assets for you - it's a "silly not to do it" task, but not everyone knows about it.
"It is also possible to precompile your templates. This will result in a smaller required runtime library and significant savings from not having to compile the template in the browser. This can be especially important when working with mobile devices."