@kettch: The biggest challenge with mobile is getting the first screen painted within a hundred milliseconds, and then AJAX loading everything else while the user isn't paying attention.

After that, it's keeping stuff out of the DOM. If you want to kill a mobile site, put lots of stuff into the DOM.

While you're building your site / app, check the checkers like modern.ie and page speed insights.

Also keep your eye on Steve Sanderson.