Start your Computer in safe mode with networking. Then start Firefox. Try Safe websites. Is the problem still there?

Starting The Computer In Safe Mode;
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Can't start this Win8.1 computer in Safe Mode with networking, only without networking. (Another thing I don't like about Win 8.)

I think when you are using e10s -- a new feature of Firefox 48-49 that separate the user interface and web content into separate processes -- that error can appear as an alternate to the "slow script" warning, but unfortunately with less detail.

We have a general support article addressing potential solutions to this issue: Warning Unresponsive script - What it means and how to fix it.

Another common cause of unresponsive script errors on Windows 7-10 is the protected mode feature of the Flash player plugin. That feature has security benefits, but seems to have serious compatibility issues on some systems. You can disable it using the Add-ons page. Either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Plugins. On the right side, find "Shockwave Flash" and click the More link. Then uncheck the box for "Enable Adobe Flash protected mode" and try that for a day to see whether it helps.

More generally:

One of the headline changes in Firefox 48-49 is e10s, which separates the browser interface process from the page content process. The performance impact of this can vary a lot between systems, so it would be helpful to know whether you have this feature turned on. To check that, either:

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, check the row for "Multiprocess Windows" and see whether the number on the left side of the fraction is greater than zero. If so, you are using e10s.

If you are using e10s:

To help evaluate whether that feature is causing this problem, you could turn it off as follows:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste autos and pause while the list is filtered

(3) Double-click the browser.tabs.remote.autostart.2 preference to switch the value from true to false

Note: the exact name of the preference may vary, but it will start with browser.tabs.remote.autostart

At your next Firefox startup, it should run in the traditional way. Any difference?

Thanks so much, every1, for the help & jscher2000, altho turning off Flash prot. mode didn't help, it turned out I was using e10s; turned it off with your easily understood instructions, restarted Ff & my whole computer, just checked about 35 sites, my email, etc. & am on Ff now & it's running great, what a relief! Thanks again, all, for the wonderful help; you all *rock*! :-)

Thanks for reporting back. It's a bit of a temporary reprieve, I'm afraid, since e10s will be permanent some time next year, but hopefully whatever is causing yours to get stuck so badly will be fixed by then. You could test after Firefox 50 is released and see whether it works smoothly on your system. If not, we probably should gather some more information to help the developers solve it.

Thanks for the info. about e10s. As you suggest, I'll test it again after the 50 release & report bk. if any problems. Thanx again, every1!

About 6 weeks ago nightly started to be very slow in changing web pages Also got a lot of messages that that web page was slowing nightly down Compared nightly to IE (win 10 on machine) and had no problems it loaded new web pages very quickly Ran malware bites it found nothing When nightly 53.0 was installed it changed pages even slower though the messages web page slowing stopped If the page that I was going to was loading some graphics it was even slower loading With the update this morning 53.0a1 (2016.11.29) (64-bit) it improved now loading much faster but still slow Start searching for more solutions page and changed browser.tabs.remote.autostart.2 preference to switch the value from true to false This seems to have fixed the problem pagers change as quick as IE A thank you to all of you

Hi bobt07, I'm not sure where Nightly users give feedback on performance problems, but hopefully you can submit something so this will be solved before Firefox 53 moves to Developer Edition.