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Firefox 65.0.2 (64-bit) slow to close under Win10

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  • 2 have this problem
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  • Last reply by Unbeknownst

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A strange problem with FF 65 under Win10/Pro 64 (1803). I'm pretty sure this is a local problem, since it doesn't appear on my other Win10 machines.

FF 65 is very slow to close, but it's not entirely obvious. I first noticed the problem when I closed FF, then about 15 seconds later I re-launched FF only to see a notification box saying that FF is already running. For testing, I tried re-launching with add-ons disabled (I have 4 add-ons, including uBlock origin), then closed FF while observing the Windows Task Manager. In the "Apps" section of the task manager FF disappears, but under "Background processes" I see 3 or 4 instances of FF, one of which consumes up to 33% CPU and up to 800MB of memory while running. These background tasks vanish after about 30 seconds.

What is FF doing at close? Is it possible to trace what happens at close?

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I think I've solved this problem. I haven't cleared my cache in some time, so I went to Options > Privacy & Security > Clear Data. The Clear Data box showed the "Cached Web Content" at 1 GB (!), so I ran the Clear data to remove all of that. I also cleared out the list of blocked pop-up windows and the list of websites that try to install add-ons. (I think these lists were created when I ran Spybot some years ago.) Shutdown is faster now, as FF no longer has to save large blobs of info.

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I am having the exact problem as yours (I also had it with previous versions of Firefox) and I don't think clearing your cache will solve it.

You can try the suggestions listed herehttps://support.mozilla.org/en-US/kb/firefox-already-running-not-responding and here https://www.howtogeek.com/131004/how-to-fix-the-firefox-is-already-running-error/ but none of them helped me eradicate this problem.

I hope there can be a fix to this other than waiting 10-15 seconds or so after closing the Firefox.

Modified by Unbeknownst

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I've been keeping an eye on the task manager, and while FF is definitely doing something after closing, the process takes less time than before I cleared the cache - usually less than 4 or 5 seconds. I guess it might depend on how long you've had FF running and/or the web sites visited. The new version 66 seems a bit better at reducing the time required to close, but I haven't done a deep investigation. For now, (for me) the short delay is tolerable.

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hurleyp said

The new version 66 seems a bit better at reducing the time required to close, but I haven't done a deep investigation. For now, (for me) the short delay is tolerable.

I just tested the new Firefox 66, and it does seem to do much better at this problem. I either didn't see it, or when I saw it the waiting time was not as excrutiating as before. I'm contemplating that this has got to do with "Extensions now store their settings in a Firefox database, rather than individual JSON files, making every site you visit faster" and "Improved performance and reduced crash rates by doubling web content loading processes from 4 to 8" entries from the changelog. Either way, I'm happy.