Use Google Libraries is a free WordPress plugin designed to leverage Google's AJAX Libraries API for improved site performance. By utilizing this plugin, WordPress sites can serve popular JavaScript libraries such as jQuery, Dojo, and MooTools directly from Google's content delivery network. This not only reduces server load but also increases the likelihood that users will have these libraries cached in their browsers, leading to faster load times. The plugin supports HTTP compression, ensuring that the libraries are served in a more efficient manner where available.

The plugin is compatible with several libraries and enhances website speed without requiring significant changes to existing code. However, users should be aware of potential compatibility issues with certain plugins like Gravity Forms and themes such as K2. Future updates are planned to address protocol-relative URLs and offer more customization options. Overall, Use Google Libraries is a valuable tool for WordPress users looking to optimize their site's performance.