Some settings Sync, so if you are using Firefox Sync, then those would transfer. However, Sync doesn't cover all settings.

Therefore, you may want to transfer the prefs.js file in whole or in part. You can read more about manual file transfers in this article: Recover important data from an old profile.

Thanks for the reply. The new computer is now ready so it's crunch time.

I know prefs.js is one of the key files I will need to preserve and transfer, but I'd swear there were more like that which I needed to transfer manually last time I did this on a Mac--but this is a PC.

How do I navigate to prefs.js on a windows machine?

And would prefs.js include the about:config settings?

Tab throbber must stay dead, and all my animation and autoplay settings need to be preserved for my sanity; this is far more important than the cookies and passwords and site-specific prefs mentioned in that article. And the article does not contain any reference to prefs.js.

I tried just copying the profile folder to a safe spot so I could then transfer it back to the new computer, but got an error message halfway through that said the name of a file was too long for the location I was copying it to....and I have no idea how many of the many items in that folder were correctly copied over, whether that was the only error, or whether, even if that was the sole item out of the thousands it said it was copying, it is important to the final outcome on the new computer.

If I do manage to copy the entire profile folder intact....does that contain the prefs.js and all the other .js and similar files that I'm remembering from past transfers?

My most recent attempt to do this resulted in a lot of wasted time and irritations over weeks before I got the tab throbbers and autoplay stuff really nailed down.

Is there no way to copy about:config specifically? The rest of it is easier to recreate.