By default Firefox download an item one-by-one when you surf a webpage. However deep inside it there’s a way on how to force it to download simultaneously.
- Start your Firefox
- On the address type: about:config
- On the filter type: network.http
- Double click on network.http.pipelining so that the value becomes true
- Double click on network.http.pipelining.maxrequests and change to higher value e.g. 30
- Double click on network.http.proxy.pipelining so that the value becomes true
Restart your Firefox and you should feel some improvement.