Use asset host for cookie-free domains for components, that make your components load faster.
Using css sprite can reduce a large number of http requests, so it makes the web page loaded much faster. It it painful to composite a lot of images manually, do it automatically.
Rails is integrated with sprockets from 3.1, which gives you the power to pre-process, compress and minify your assets. It's awesome, but it slows down deployment a lot.implemented