wp rocket

I have multiple WordPress websites, all of which utilize WP Rocket. Upon installing an additional Memcached plugin, I noticed a slight improvement in website loading speeds. How can I accurately calculate the loading speed differences both before and after the installation of Memcached...

I am using wp super cache and it is a free version to speed up my wordpress site but I know that Wp rocket is a good one too, especially to speed up woocommerce site which I am using now, but it is a paid version without allowing users to use it as free trial. What do you have any experience...