I was building a new webapp and realize that somehow that there is a _dd_s cookie being injected.

Then I realize that this cookie is still injected on blank websites such as https://example.com and feared that it might be Chrome extension malware... plus the cookie isn't injected when using Chrome incognito...

However, knowing from past experience, I immediately suspected the Evernote Web Clipper which has a horrible past history such as slowing down every webpage with deprecated DOMNodeInserted, injecting styles and fonts causing noisy Content Security Policy issues, etc... and yup, disabling the extension solves the issue.

The problem didn't exist on version 7.19.0 and only started on version 7.20.0, I don't know why Evernote chose to put their extension state in the website's cookie store and slow down every HTTP request...