How can I improve TTFB of 4 seconds? Does it have something to do with CF?

Are there settings on CF which I can change for shorter TTFB?

Are there any tools with which I can detect what is causing this on my Wordpress site?

Try the Cloudflare Speed Test

My own site’s initial response time (the gray circle to blue) is way higher than any other site I visit. Even completely new sites. My internet speed is the same, its my site that responds very slowly.