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speedtest on firefox is slower than a speedtest on internet explorer i'm talking the halve slower...


when i do a speedtest on speedtest.net i should see a speed result of above 100 mbit cause my connection is 120 mbit down

in firefox its always halve like 50 mbit max and in internet explorer it shows the correct speed...

before i never had problems with firefox but with the new updates not...

Chosen solution

speedtest uses flash for speed measurements & adobe has introduced a special protected mode for its flash plugin only for firefox, which might cause slowdowns when there is interference between the following processes (so you might not observe it on IE or other browsers): firefox.exe, plugin-container.exe & FlashPlayerPlugin_11*.exe - please make sure that norton's firewall or av-engine isn't blocking/sandboxing them in any way.

alternatively you can also try disabling the protected mode for adobe flash & see if this is making a difference...

Read this answer in context 2

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Installed Plug-ins

  • Shockwave Flash 11.5 r502
  • The QuickTime Plugin allows you to view a wide variety of multimedia content in Web pages. For more information, visit the QuickTime Web site.
  • NVIDIA 3D Vision plugin for Mozilla browsers
  • NVIDIA 3D Vision Streaming plugin for Mozilla browsers
  • Next Generation Java Plug-in 10.9.2 for Mozilla browsers
  • Windows Activation Technologies Plugin for Mozilla
  • NPRuntime Script Plug-in Library for Java(TM) Deploy
  • Adobe Shockwave for Director Netscape plug-in, version
  • Adobe PDF Plug-In For Firefox and Netscape 10.1.4
  • Adobe Shockwave for Director Netscape plug-in, version
  • 4.1.10329.0
  • The plug-in allows you to open and edit files using Microsoft Office applications
  • Office Authorization plug-in for NPAPI browsers
  • np-mswmp
  • Yahoo! activeX Plug-in Bridge


  • User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20100101 Firefox/17.0

More Information

Question owner

Do you perhaps also know how to get rid of the bug that causes all your right click options in firefox to go black?

Thats one annoying problem :S

Modified by broken

PeterB1970 0 solutions 5 answers

Yeah, I edited it cos it wasn't that clear. Just added a couple of line-breaks.

Not sure about the right-click problem.

Modified by PeterB1970

higgslane 0 solutions 1 answers

Try using speedtest.btwholesale.com I discovered the problem on my PC running XP was being caused by the AVG 2013 (free version) WEB Brower protection. Speedtest.net was showing half the speed when using Firefox. speedtest.btwholesale.com showed the correct speed. Curiously my other PC running Windows 8 doesn't show the problem even using the same versions and options of Mozilla and AVG.

Modified by higgslane