I disabled all features on the cloudflare server except the proxy, they are useless on the free plan, and I configured everything on my server. Because of this, I wrote to our guy in this one XF2 Guides - Ultimate Guide to Faster + Responsive Forum [Minify+Htaccess+Cache+Phone+FA5] -21673 that you shouldn't use cloudflare unless you need to hide your ip address.You're right, when I disable cloudflare my website gets 96~100% and when I enable it I get 65~76 that's weird because same tests are made on https.
Problem seems to be from Cloudflare I guess, but still didn't get it