What does “Blocked” really mean in the Firefox developer tools Network monitoring?

Question

The timing section of the Firefox Network Monitor documentation, \"Blocked\" is explained as:

Time spent in a queue waiting for a network connection.

Answer 1

We changed the Firefox setting (about:config) 'network.http.max-persistent-connections-per-server' to 64 and the blocks went away. We changed it back to 6. We changed our design/development method to a more 'asynchronous' loading method so as not to have a large number simultaneous connections. The blocks were mostly loading a lot of png flags for locale settings.