No issues in default chrome, however, the problem in Firefox and Comodo Dragon persists. I have tried clearing my cache and cookies again, which didn't help.
Edit: I have the same problem on Github, so the problem is indeed related to Gravatar.
Edit 2: The problem is related to browser extension Ghostery. It appears that just recently they added a block option for Gravatar and all trackers are enabled by default.
According to Ghostery's website, they have 20 million people using the extension and most of them probably auto update their blocklist. Bad news for gravatar. https://www.ghostery.com/