What happens is that every time I hibernate my laptop (with Windows 7 Pro, 64bit), when I resume from hibernation, FF is completely unresponsive (hangs) for minutes. Easily around 5 minutes. Eventually a dialog box pops up with the following:
"A script on this page may be busy, or it may have stopped responding. You can stop the script now, or you can continue to see if the script will complete."
And the two buttons are: "stop script" or "continue". After I click "stop script" the unresponsiveness finally goes away, and FF starts working normally again.
I think possibly even clicking "continue" also makes it go back to normal, but I'm not sure anymore since I have recently just switched to sleep mode out of frustration in order to not deal with it anymore, and I don't remember exactly if I get the same result from clicking either option.
Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).
Do not click the Reset button on the Safe mode start window or otherwise make changes.
Ok so I finally got around to testing this thoroughly, as you suggested. I used FF in SafeMode for about 2 days now, and went through at least half a dozen hibernation/resume cycles. Probably closer to 10. I can conclude that using safe mode (aka restarting with all add-ons disabled) did not solve it at all. The issue remains.
As always, simply resetting FF (either with enabled or disabled addons) seems to make this problem less severe, if not almost go away completely. But after a few hibernate/resume cycles, it becomes really bad. Before posting this, I was using Opera for like 10 minutes after resuming from hibernation before FF finally snapped out of it, and windows that I had clicked on in the task bar, like 10 minutes ago, finally popped up.
I have not yet tested the disabling hardware acceleration. Sounds quite doubtful that it might help but I'll try.
How can we get the developers' attention on this?
33 others report having this problem (as of this post). And there are similar reports elsewhere. But after many new versions of FF, it seems that the developers are not addressing these bugs but are instead focused on new features to compete with whatever Chrome rolls out.