Mozilla Firefox 3 beta 5 will, when it comes out, have some improvements in connection parallelism.
Just like IE8 increase from 2 concurrent connections per host to 6, Mozilla Firefox will also increase it to 6. The about:config entry for this is "network.http.max-persistent-connections-per-server".
Furthermore the max number of HTTP connections will be increase from 24 to 30. The about:config entry for this is "network.http.max-connections".
The number of HTTP connections that can be established per host will go up from 8 to 15. The about:config entry for this is "network.http.max-connections-per-server".
If you using Firefox from behind a proxy then the max number of concurrent connections will be increased from 4 to 8. The about:config entry for this is "network.http.max-persistent-connections-per-proxy".
All in all this will make Firefox 3 beta 5 even faster. These changes are needed since, according to Mozilla developers:
Sites are demanding more connections due to JS traffic, and we're using up more of the total connection limit with suggest requests, antimalware, extension traffic, etc.




