This small plugin (5 Kb) loads the stylesheets asynchronously and improve page load times.
The recommended use of this plugin is to load your vital stylesheets synchronously and non-vital CSS files asynchronously.
Non-vital CSS-files can be for example: fonts, icons, before the fold template-specific CSS, etc.
You can choose which files to load synchronously with a filter in your function.php, eg.:
// exclude main and child stylesheets from delivery optimization
function exclude_from_delivery_optimization($handle){
return in_array($handle, array('main-stylesheet', 'child-stylesheet'));
}
add_filter('speed-up-optimize-css-delivery', 'exclude_from_delivery_optimization');
Note: this only works if your other plugins and theme add the CSS correctly.