I have two versions of my site up on the same server, one on a staging subdomain that is not proxied or cached by Cloudflare and the other on the main domain, that is proxied and cached by Cloudflare. I am seeing a consistent increase in Time to Interactive (TTI) and thus Total Blocking Time (TBT) on the main site proxied and cached by Cloudflare. I am seeing on average around a 15% increase in TTI.
I am seeing this from Google Page Speed Insights, WebPageTest, and PageSpeed Compare.
As you can see there’s a 119% increase in TBT but all over stats are favorable.
I have Cloudflare’s RocketLoader turned off, as it was hindering performance.
What is causing this? How can it be fixed?