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

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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...

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Site Moderator

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

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...

23 REPLIES
Legendary Contributor

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

Update your firefox to Firefox 18 and check it out...

New Contributor

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

there's a slight improvement but when i test it more than 1 times sometimes its back to unstabile, and in iE it stays stabile.

Site Moderator

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

hello, could you tell us which kind of security software is running on your pc?

New Contributor

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

norton internet security 2013

New Contributor

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

Its really hard to get an accurate speed test meeting in firefox always shows 60 Mbit and in IE it always goes way over 100Mbit...

When i tested it 5 times with the new firefox version 18 out of 5 imes it went 1 time over 100Mbit which was a good result of the speedtest. But now its showing way lower agin... Likz 50 , 60 Mbit

And if i test it 10 times with IE i get overal the same results.


I also noticed the flashplayer from http://www.speedtest.net/ is like hanging its not fluid at all and i updated that aswell..

Just tested it the flashplayer with the speedtest in IE and agin stabile as hell... Nothing like the problems FF is showing me.

Site Moderator

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

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...

New Contributor

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

Well @madperson your trick solved the problem i had for ages... With the flashplayer on ProtectedMode=0 it works like a charm. Now my question is do i have to leave the flashplayer like this? on ProtectedMode=0?

Support Forum Moderator

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

Hi broken,

In light of your post above I have taken the liberty of marking the thread solved with madperson's answer.

Unfortunately Firefox (Windows) has been having problems with protected mode and FlashPlayer for some months now. Turning off protected mode is not ideal, and some users find it a rather difficult procedure, but until and unless a permanent fix is available from Adobe FlashPlayer then it may be necessary to turn off protected mode.

You could also consider speeding things up by not using FlashPlayer unnecessarily, maybe considering something like no-script to block unwanted instances. (The click to play feature may also be useful https://blog.mozilla.org/security/2012/10/11/click-to-play-plugins-blocklist-style/ )

Site Moderator

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

unfortunately this is most probably influenced by external factors so mozilla can't do much about addressing the issue...

i'm not familiar with norton's software, but we had reports that other security software (old versions of f-secure) did intefere with the flash protected mode and cause cause slowdowns when a function named "enhanced process monitoring" was enabled.

you might want to try setting ProtectedMode=1 again and experiment with your norton settings - in case there is an options to whitelist certain applications from in-depth scanning/sand-boxing/etc please add firefox.exe, plugin-container.exe (located in the mozilla firefox program folder) & FlashPlayerPlugin_11*.exe (located in C:\Windows\SysWOW64\Macromed\Flash) to this list.