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New versions of Firefox are very slow for download speeds. 50% of what is available from my provider. Safari is at 100%. Is this from security and filters ?

  • 6 replies
  • 5 have this problem
  • 118 views
  • Last reply by FredMcD

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Recently updated to the latest 2 versions and Firefox is failing download speed wise. Upload speeds are what they should be. I have ran speed tests from multiple sources and all return a similar range - 40-60Mbps. My provider speed is 100Mbps. I have run the same tests with Safari and it is operating at 100% speed wise. Are new security features and / or tracking filters responsible for this slow down ?

All Replies (6)

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Are you using a download manager add-on/program?


Start Firefox in Safe Mode {web link}

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


This download manager works separately from the browser. The browser tells it what to download, and off it goes.

http://www.freedownloadmanager.org It is a powerful modern download accelerator and organizer for Windows and Mac.

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I have the same problem, significantly reduced download speed, only in Firefox, both on Windows and Linux. Safe Mode made no difference.

Modified by zoltan.k81

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I'm using Firefox 78.0.2. I have Cox an an ISP, with a fiber install for 500 down/up. When I use speedtest.net, I only see speeds of 40 down, .8 up; very slow. When I use speedtest.net on Edge or other browsers, I see speeds consistently over 400 Mbps. What's the problem running this site on Firefox?

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The same problem here. I use Firefox Browser 79.0(64-bit)1 installed on Windows 10 (64-bit). Download speed with Firefox - 20 Mbps, with Opera and Microsoft Edge - 60 Mbps. Measured download speeds are the same, when measured with speedtest.net and fast.com. Starting in Safe mode doesn't make change.

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Recently I'll be online for over an hour, and gradually my speed drops and finally, hangs up both Firefox 80.0.1 and even my widows 10. Disc usage maxes out to 100%, and in Task Manger, I see at least a half dozen instances of Firefox, under the Processes tab. This seems to happen mostly the worst on Facebook.

Modified by mzpupper

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https://support.mozilla.org/en-US/kb/firefox-slow-how-make-it-faster

https://support.mozilla.org/en-US/kb/firefox-uses-too-many-cpu-resources-how-fix

https://support.mozilla.org/en-US/kb/firefox-uses-too-much-memory-ram

https://support.mozilla.org/en-US/kb/firefox-hangs-or-not-responding

https://support.mozilla.org/en-US/kb/firefox-takes-long-time-start-up

https://support.mozilla.org/en-US/kb/quick-fixes-if-your-firefox-slows-down


MemTest LAST UPDATED : 12/04/2020 Could you please run a tool from http://memtest.org/ in order to check the integrity of your RAM?

You will need a thumb or disk drive to install it on.


Do you let Windows handle the page file or did you set a fixed size ? If you use a fixed size for the page file then try the former and let Windows handle the page file.