Can you mention a couple of the affected sites? They might use the same service (e.g., DISQUS). Sometimes other Firefox users have reported issues with a particular service that can help get to resolution more quickly. There are a number of add-ons that can filter externally loaded content, either for your security or to reduce annoyance. A standard diagnostic to bypass interference by extensions (and some custom settings) is to try Firefox's Safe Mode. More information: [[Troubleshoot Firefox issues using Safe Mode]]. You can restart Firefox in Safe Mode using: Help > Restart with Add-ons Disabled In the dialog, click "Start in Safe Mode." If the comments load correctly, this points to one of your extensions or custom settings as the problem. Any change?