Use the 'ember-rails', 'ember-source' and 'ember-data-source' gems.
Adjust scrolling demo styling.
Make infinite scroll trigger 50 pixels before scroll limit.

This should help to reduce the impact of latency by triggering
the server call (when implemented) before the user reaches the 
scrolling limit.
Delete unnecessary twitter bootstrap files.
Create an application wide ember template.
(it's like a rails layout)