[somat]

my guess is filtered dns.

I just audited my system(firefox 110 on openbsd). and when dns is acting up(I disabled external dns leaving only my internal domains resolvable) firefox takes forever to do anything waiting on dns timeouts.

firefox is making requests to

  www.google.com #why? I don't have google set as my default search engine.
  detectportal.firefox.com
  9.9.9.9.https  #???? this is strange. DoH? but I should have it disabled.
  contile.services.mozilla.com.        
  firefox.settings.services.mozilla.com.
  content-signature-2.cdn.mozilla.net.
  push.services.mozilla.com.

And I probably missed a few.

Well, Sigh, I have a new weekend project. poking around in about:config trying to turn this bullshit off off.

[JohnFen]

That's entirely possible. It does smell like something's waiting for a timeout of some sort. But the times are very long. About 5 minutes to start the browser, and while not every page render incurs a delay, when they do, the delay is on the order of a minute or so.

In any case, I really have spent a lot of time digging into this. At some point, I just had to let it go.