[amiraliakbari]

The "Railgun" feature mentioned in the article is only available in some paid plans. Using the free plan wouldn't keep an open connection between your servers and Cloudflare's. It does improve the situation by terminating users' handshakes early, using better links, warm DNS cache, etc. among servers. But the latency hard limit is still present between your server and CF. Skipping https between your server and CL is not an option either for any site transferring user data.

[chatmasta]

Ah, I see. I did not realize that. Accordingly, I edited my comment to be less inflammatory. :)

I understand that by using the generic CF free cert, https terminates at CF and the connection CF->Origin is over unencrypted HTTP. Is this why there is latency overhead? Because CF cannot connect to origin via https so it cannot open a persistent tunnel? Or is it because the overhead of keeping an open https tunnel per origin server is prohibitively expensive to maintain for every free customer?

I assume that even though there is no persistent tunnel, CF still must still use persistent TCP connections?

[floatboth]

Maybe the cost is not completely prohibitively expensive but they do consider it a premium feature. Have to earn money :D