Fooman Speedster Advanced is a free extension which has been tested with the default Magento themes. This extension can help you to:

– Speed up your store by combining, compressing and caching Javascript and CSS files.

– Combine multiple Javascript files into two separate files (one static and one variable), and combines multiple CSS files into a single CSS file, for faster page load times.

– Have a fully automated running once installed, with automatic versioning when Javascript/CSS files are updated.

–  Have improved speed performance relative to the classic Fooman Speedster extension.

– Optimise the theme to help implement a smarter caching strategy (for Magento version 1.5 and above).

– avoid problems with PHP overhead when compared to the classic Fooman Speedster extension (files are created, but not served, via PHP).

– Use different domains for Skin CSS, allowing the CDNs (Content Delivery Networks) and cookie free domains.

– Have multi-store capability.

– Use the Minify library by Steve Clay (released under a BSD license).