The third tab stays blank/never finishes loading, or is there is an error message? Firefox does have a cap on the number of connections it keep open with a single server, but I don't think that is a recent feature. If you want to experiment with that setting, here's how: (1) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button accepting the risk. ''More info on about:config:'' [[Configuration Editor for Firefox]]. ''The moderators would like us to remind you that changes made through this back door aren't fully supported and aren't guaranteed to continue working in the future.'' (2) In the search box in the page, type or paste '''network.http.max-persistent-connections-per-server''' and pause while the list is filtered (3) Double-click the preference to display an editing field, and increase the value from 6 to, say, '''10''' then press Enter or click the blue check mark button to save the change. Not sure whether that takes effect immediately or after a regular shutdown/restart of Firefox.