Have you ever tried concatenating your JavaScript and CSS files for performance improvements? The idea is that latency is a bigger issue than file size when loading web pages, so stuffing all your JavaScript into a monolithic file for deployment should improve performance.
I wrote a rake task to do this for some of my applications (such as tiktrac). This is slightly more cumbersome than a feature I spied in the ActionPack changelog:
Added caching option to AssetTagHelper#stylesheet_link_tag and AssetTagHelper#javascript_include_tag [DHH]. Examples:stylesheet_link_tag :all, :cache => true # when ActionController::Base.perform_caching is false => stylesheet_link_tag :all, :cache => true # when ActionController::Base.perform_caching is true =>...when caching is on, all.css is the concatenation of style1.css, styleB.css, and styleX2.css. Same deal for JavaScripts.
Read more in the asset_tag_helper.rb source.