cd c:\Program Files\Mozilla Firefox
 set MOZ_PROFILER_STARTUP=1
 set MOZ_PROFILER_STARTUP_ENTRIES=20000000
 set MOZ_PROFILER_STARTUP_INTERVAL=100

 firefox.exe

 Recording started: Sat 17 Feb 2024 12:58
 Recording length: 1m12s 

I run the latest Firefox (v122.0.1) on Windows 11. Since last week, FF takes 14 minutes to start the first time after a boot. :-( Usually FF starts in ~3 seconds. I reboot the laptop. I wait a minute. I start FF. Nothing happens for 14 minutes. Finally the browser window suddenly appear and everything is working normally. I exit FF (no remaining firefox.exe processes are running). I start FF again. Now it starts immediately as usual. :-) But: I reboot and start FF. Again, it takes 14 minutes to start. This is reproduceable every time. I haven't tried to *solve* this by refreshing FF or simillar. Right now I'm more interested in debugging this and finding out what is wrong. I found https://profiler.firefox.com/docs/#/./guide-startup-shutdown which states how to automatically start the profiler at startup. 12:40 I boot the computer, login and wait a minute. 12:43 I start CMD.EXE and run: cd c:\Program Files\Mozilla Firefox set MOZ_PROFILER_STARTUP=1 set MOZ_PROFILER_STARTUP_ENTRIES=20000000 set MOZ_PROFILER_STARTUP_INTERVAL=100 12:44 I run: firefox.exe No GUI appear. (it won't appear until 14 minutes later) I open the Task Manager and see one (1) firefox.exe process, taking 0% cpu. (pid 17668) 12:48 One more process running for a few seconds. Commandline is just "c:\Program Files\Mozilla Firefox\firefox.exe", no more options. 0% CPU. 12:50 One more process running for a few seconds. Commandline is just "c:\Program Files\Mozilla Firefox\firefox.exe", no more options. 0% CPU. 12:52 One more process running for a few seconds. Commandline is just "c:\Program Files\Mozilla Firefox\firefox.exe", no more options. 0% CPU. 12:54 One more process running for a few seconds. Commandline is just "c:\Program Files\Mozilla Firefox\firefox.exe", no more options. 0% CPU. 12:56 One more process running for a few seconds. Commandline is just "c:\Program Files\Mozilla Firefox\firefox.exe", no more options. 0% CPU. 12:58 The browser GUI finally appear. Everything is now normal. It is showing one (1) tab with my start-page (google) just as it should. (my Task Manager now show 12 FF processes running, with various options) 12:59 I click the icon to stop the profiling. I open the profile. [Profile Info] says: Recording started: Sat 17 Feb 2024 12:58 Recording length: 1m12s So my profiling data don't show what happens between 12:44 to 12:58 :-( Just for the sake of it, I'm attaching a pic of the first 10 seconds of the profile (at 12:58). PS: Between 12:44 and 12:58 no FF window exists at all. Alt+Tab show no FF and in Task Manager I can't do any "Window" management, it is greyed out. I.e. no FF window exists for this process. Question 1) What should I do to debug what happens between 12:44 and 12:58? Question 2) How can it be that it takes 14 minutes to start FF from scratch (boot) while it starts quickly (~3 seconds) if it has been started once? I mean, all firefox.exe processes are gone when I exit FF, so starting FF again should be like starting from scratch, but apparently something is different. Question 3) Is it normal that a FF, with only one tab (https://google.com/), run 12 processes in Task Manager?