Open about:config in a new tab and make the following changes:
- network.http.pipelining -> True
- network.http.pipelining.maxrequests -> 10
- Anywhere on the screen, right-click and add a new integer: nglayout.initialpaint.delay -> 0
- If you’re using a proxy, also change the proxy versions: network.http.pipelining.proxy.pipelining -> True
WARNING: Be conservative when setting your pipelining settings. To the untrained eye this feature looks like a DOS attempt on the server side and might get you blocked.