It also happens when the hosts file is messed up and the system can’t resolve its own hostnames. Opensuse used to be pretty notorious for doing something odd to the hosts file by default that really only affected Firefox.
Edit: the increased security they’re trying around the browser might also be triggering that local resolution issue
Any issues lately with your network? When DNS is down or having issues, Firefox and forks take forever to start up.
Nothing special, I don’t think that’s the problem since the lag is at every launch and it takes something like a minute to appear.
It also happens when the hosts file is messed up and the system can’t resolve its own hostnames. Opensuse used to be pretty notorious for doing something odd to the hosts file by default that really only affected Firefox.
Edit: the increased security they’re trying around the browser might also be triggering that local resolution issue