I believe it was LinkedIn who took a hybrid approach a while back. I have no idea if this is still the way things are done, but somewhere in the 2012/2013 time period they would in general render things server-side. If the site was having load issues, they would turn the server-side rendering off and then the clients would render instead.

This was achieved using their fork of DustJS: https://github.com/linkedin/dustjs

   Asynchronous Javascript templating for the browser and server