I found out – to my big surprise – that I was running Firefox with the default settings and not the tweaked settings. I had the feeling that Firefox was running slower than before after the latest update but I was not able to determine the cause, until now that is.

I would suggest you take a look at the following settings as well and see if you are using Firefox with tweaked settings or the default ones. If the latter is the case I suppose you change the settings to the same values that I changed them to, again..

Type in about:config and filter the name network.http.pipelining. The default values are that network.http.pipelining is set to false and network.http.pipelining.maxrequests is set to 4.

If your settings are optimized network.http.pipelining should be set to true and network.http.pipelining.maxrequests to a value of 30, 32 or 34.

After that filter for browser.turbo.enabled. If no result comes up you don’t have that setting yet. Right-click the blank space and select New > Boolean from the menu. Name it browser.turbo.enabled and set it to true.

If you happen to make a mistake, e.g. create a String with the name browser.turbo.enabled, you can correct it by navigating to your Firefox profile folder and edit the prefs.js file by hand. Just search for the line and delete it. Close Firefox before you edit the file.