The server still does all the heavy resource intensive stuff, the "business valuable" part. He is just moving templating and managing of state to the client. I

The server still does all the heavy resource intensive stuff, the "business valuable" part. He is just moving templating and managing of state to the client. I have the impression though, that a single page app will reveal problems like increased memory usage where in the classical way of writing webapps would be hidden by the constant page reloads (where hanging objects would get GCed anyway).