ClickFunnels uses a CDN (Content Delivery Network) of Cloudflare and Amazon.
What it does are 2 main things.
The first one is it gives you the ability to enable SSL to your webpages.
SSL is a security layer for your webpages with the protocol of https
This Security Services protect and secure Internet applications and APIs against denial-of-service attacks, customer data compromise, and abusive bots.
That makes search engines rank your webpages higher in the organic ranking (Google and other search engines love secure webpages).
And it lets you take payments straight for your webpages (no need to go to other secure page for receiving credit cards payment), because your visitors/prospects don't have to worry from any theft.