When you switch on your Mac…
Click on the network icon (e.g. the wifi icon for most people) and click “Turn Airport off”.
Then start Firefox.
Click on the network icon and select “Turn Airport on”.
You will find that Firefox starts up 10-100 times faster, with fewer crashes, and OS X will run faster, with fewer delays for the next couple of minutes.
Why? Firefox caching ain’t doing what it should be doing…although in some cases, I’m still not sure why
(rest snipped while I check in more detail what’s happening)