The goal of plugin is not to increase site performance but it tries to remove WP footprints from your source code. There are two types of minify in the plugin:
1) Compress HTML: it removes HTML comments usually generated by themes and plugins and also decrease readability of the code
2) Minify stylesheet: it only minify “style.css” so theme info will be hided!
As you may know minification is a complex task. Most of minify plugins don’t work properly in most situations. We try to provide three different modes for it (and still some customers has problem because of invalid HTML syntax in their theme and the complexity of the task!)
As I said I only focused to remove WP, plugins and themes footprints but this doesn’t mean you can’t use other third party plugins to minify. (Read FAQs for details)