Solved
Minify JS CSS
Turning minify to ON using com.adobe.granite.ui.clientlibs.impl.HtmlLibraryManagerImpl is doing ONLY basic minification. For example carriage return is not removed from CSS and JS
Even obfuscation is also basic.
If there a way to configure the YUI compressor that it uses with advanced parameters for more compression of the statis files (JS and CSS) ?