What's your computer system and Firefox version?

This may be of help, and the crash report might tell us something.

How to crash Firefox (All Systems); Instructions here; https://developer.mozilla.org/en-US/docs/Mozilla/How_to_report_a_hung_Firefox

This link has a program that can crash Firefox.

Start Firefox in Safe Mode {web link} by holding down the <Shift> (Mac=Options) key, and then starting Firefox.

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

I loaded multiple animated gifs I then ran crashfirefox.exe Firefox didn't crash about:crashes shows no crashes

I'm running Windows 10 Pro, Firefox 58.0.2

If I start in Safe Mode, open animated gifs, end FireFox, I still see tasks still running (looks like 1 per gif)

I called for more help.

Please provide public link(s) (no password) that we can check out. No Personal Information Please !

It's not unusual to see six firefox.exe processes but 10-15 seems odd to me.

What if you set the content process limit to 4 (default setting), using the steps in this article: Firefox's performance settings?

When you close a tab, Firefox may not spin down the processes used by that tab right away if other tabs are using that process. When you exit the program completely, I would expect the processes to shut down in 10-30 seconds. If they aren't closed within 60 seconds, I think a watchdog process will kill them and present a crash dialog so you can report a hung shutdown.

I checked process limit and it was set to default 4. I loaded gifs via http and found that FireFox tasks properly cleaned up after being closed. The issue occurs when loading images from local drive.

I used these as a test: https://78.media.tumblr.com/ad15e3c4ce69b2065d4bb1eb46da221f/tumblr_oyveyexvvB1vmobp0o1_400.gif https://78.media.tumblr.com/1b902d8f93c35062deb7bd46a51ab322/tumblr_p2xgl03OIt1viuar9o1_1280.gif https://78.media.tumblr.com/a93edb4101b3ce84d93edddfc5de6403/tumblr_osyk3sYyHu1vmobp0o1_400.gif https://78.media.tumblr.com/1dd02a619513b5bdb949d62807849fbc/tumblr_oljj6fCiua1sxw6mio2_r1_500.gif

I saved them locally, and loaded them (double clicked, FireFox is the default app for images) up to 10 times. Attaching screenshots of task manager 1) while FireFox is running, and 2) after closing FireFox and waiting 3-4 minutes.

Wow, nice pics.

I'm puzzled by all the extra processes that seem to be "dead." Does this only occur when you let Windows launch Firefox? Or in other words, if you use the following methods, does the problem not occur:

• in Firefox, menu > Open File (Ctrl+O)
• drag and drop the GIF onto a Firefox tab

If those work normally, there may be a problem with the way the shell command is set up for GIFs, not that you had any control over how Windows did that...

Nice catch. Start FireFox, "Open File" on each of the gifs, close FireFox, no issues. Drag and drop to FireFox, close FireFox, tasks left running.