Hi, I hope I’m not late for the party.
I’m a developer specialising in speed and worked extensively with Cloudflare. In my opinion, you’re asking the wrong question because you don’t understand how things work. Let me explain.
So major flaw in your question is:
GTmetrix waterfall show that initial response from the server is 3 secs!!!
A website’s initial response (TTFB) depends on the server because the server is generating HTML. And what influences how long TTFB will take? First, it’s a distance from a user to the server and then how the website has been built. When it comes to how the website has been built is most important how many lines of code it has to process, what’s server’s CPU single-thread performance, CPU load, how quickly gets data from the database, and a few more but these are most important.
I really hope you understand on this point that there is an issue with your server or how the website has been built, right? Now, to solve this, you’re trying to fix this by adding a CDN. OK, let’s talk about CDN and Cloudflare
Cloudlfare is a CDN, DDOS mitigation and Firewall mainly, it can help a bit with its optimization features like mirage and rocket loader but it’s not a silver bullet. Cloudflare’s optimization it’s just a little extra to its core purpose of Content Delivery Network. And actually, they never said: “However your website is made, using Cloudflare PRO will make it really fast”. So when it comes to TTFB, Cloudflare can only help with static pages and has to be set that way. If your website is an e-shop, it’s probably dynamic and full-page caching may cause more harm than good. And then if you solve enabling full-page caching for a visitor, when he/she put’s anything to the cart, a full-page cache must be turned off and you’re where you been.
And when we’re talking about speed, TTFB is just one part, font-end code (HTML, images, fonts CSS and especially JS size) is as much important as fast TTFB. JS is the main killer really because it’s overused and it’s very hard to do anything about it. Everything else is relatively easy to optimise. So even if you have 1ms TTFB, if your front-end need to load 4MB of JS to render the website, you still have a slow website, and Cloudflare or any other service won’t help.
So I hope you understand that you made a wrong assumption on what Cloudflare can and can’t do for you. It’s a tool, works very very well for some cases, good for others and there are cases that it doesn’t help at all.
Now, why do slow websites exist? My observation is that slow websites haven’t been planned to be fast in the first place. Speed wasn’t on the top of the list of requirements when the building process has started. And then, who did it, most probably had no previous experience and training building fast websites.
So what to do about it? The best, long term solution is to rebuild from scratch with speed as a top priority. Anything that would significantly interfere with the speed cannot be used. In other words, instead of fixing a large engine to Ford Fiesta, a better solution is to build Formula 1 from the very beginning.
I hope that helped.