Tested your free version on my test site and have to say that the second load is much longer than first load. Does this make sense after accessing a cached page?
See attached screenshots please. This is my site for testing: https://www.socialmediaschule.org
Hint: Use WP 4.8.2, BP 2.9.1, JCH Optimize Pro, ImageRecycle and a CDN
"For now, your plugin does not beat other caching plugins"