Gonzalo Ayuso has a handy performance tip for getting that little bit extra speed from your page load times - combining Javascript with PHP files.

One of the golden rules when we want a high performance web site is minimize the HTTP requests. Normally we have several JavaScript files within our projects. It's a very good practice to combine all our JavaScript files into an only one file. [...] But if your project is alive and you are changing it, it's helpful to spare your JavaScript files between several files. [...] So we need to choose between high performance and development comfort.

He includes a quick script that runs through your javascript directory (recursively), grabs all of the javascript content from each, combines and minifies them to serve gzip compressed out to the browser.