Few simple rules:
- Combine selected libraries and their plugins in to a one file
- Minify that file
- Compress the minified file with Gzip
- Check with your web site session initialisation if the visitors browser supports Gzip
- Offer either of the files depending of the visitors capabilities.
The server side checking of browsers support for Gzip could be done with the following PHP code:
$_SESSION['gzip'] = false;
if (isset($_SERVER['HTTP_ACCEPT_ENCODING'])) {
if (strpos($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip') !== false) {
$_SESSION['gzip'] = true;
}
}
Similarly you could compress CSS files too. For this you could try the YUI compressor.