CC-Minify

The CC-Minify plugin optimizes your website’s CSS and JS files by combining, minifying, grouping and caching them to speed up your page’s load time.
This plugin uses the Minify PHP library.
Additionally using Apache with mod_rewrite (or other server supports URL rewriting) it can rewrite URL to simplify the CSS and JS paths, for example:
from: http://example.com/wp-content/cache/styles/all.css to: http://example.com/styles/all.css
from: http://example.com/wp-content/cache/scripts/head.js to: http://example.com/scripts/head.js
This plugin is compatible with Multisite WordPress installations.

Tips & Tricks

You can check if a css and/or js files has been served from a cache by opening the page’s source code.
If files are served from cache, you should see a comment with the date and time when it was last cached, for example:

Requirements

1. Server supports URL rewriting: Apache with mod_rewrite, IIS 7.0+ permalink support or nginx.
2. Read/Write access to wp-content/cache directory.
3. PHP interpreter version >= 5.3.