Frank Goossens on "[Plugin: Autoptimize] No Reduction in total size"

OK, had a good look, these are my conclusions;

There indeed is only a slight reduction in total CSS-size (currently; 321.995 -> 321.219). the reason is that almost all your css (e.g. the 3 big ones; /wp-content/plugins/jetpack/css/jetpack.css, wp-content/themes/incognito/style.css and wp-content/themes/incognito/css/woocommerce2.css) are already minimized. In this case AO's minification (which is not the same as compression) cannot improve on the filesize, only the number of requests can be reduced (from 14 to 3).

As such, the message;

You may have too many css files (3 files found)

Should more logically read "You may have to much CSS" or "Your CSS-files may be too big". I'll reach out to Patrick (Sexton) to improve ;-)

Reducing the number of files (both CSS & JS) does have a huge performance impact, compare the results of a webpagetest.org test of your site with and without autoptimize.

hope this clarifies,
frank