When I start Firefox without any internet, i.e. Airplane mode, the browser starts up pretty quickly. However when I connect to internet, either via WiFi or LAN, the startup time increases dramatically. This means that Firefox is connecting to the internet, waiting for some server to respond and then finish the launching of the browser. I have been able to figure out that Firefox connects to the following URLs when it launches. # cdn.statically.io # img-getpocket.cdn.mozilla.net # ublockorigin.github.io # aus5.mozilla.org # content-signature-2.cdn.mozilla.net Please note that this is not the complete list, it is just what I have been able to figure out. There might be other URLs that Firefox connects too, which I am not aware off. So my questions are as follows 1) How do I come to know all the URLs Firefox is connecting too, when it launches? 2) How can I check how much time does the server take to respond back to Firefox? 3) Is there a way that to stop the connection between these servers and Firefox? For example, pockets is getting shut down and I do not use pockets. So I maybe the connection to img-getpocket.cdn.mozilla.net can be terminated or stopped. OR maybe the connection to content-signature-2.cdn.mozilla.net can be asychronous and need not hold up the browser loading and so on