Using mod_concat to Speed Up Start Render Times

The most critical part of a page’s load time is the time before rendering starts. During this time, users may be tempted to bail, or try a different search result. For this reason, it is critical to optimize the head of your HTML to maximum performance, as nothing will be visible until it finishes loading the objects inside.

One easy way to speed up rendering during this crucial time is to combine your CSS and JavaScript, saving the performance tax associated with every outbound request. While easy in theory, in practice this can be difficult, especially for large organizations.

http://www.artzstudio.com/2008/08/using-modconcat-to-speed-up-render-start/