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

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.

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

norton internet security 2013

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.

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...

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?

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/ )

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.

But what does protected mode 0 do can it be harmfull if i leave it like this?

What can happen?

protected mode is an additional security measure introduced by adobe 6 months ago that makes flash content run in a container with low rights to make it harder for malicious code to infect other parts of the system...

for more technical details on it see http://blogs.adobe.com/asset/2012/06/inside-flash-player-protected-mode-for-firefox.html

I'll leave it like this than, thanks to all the people who helped and replyd.

Thank u.

I had this problem to since 11.3 came out. 11.2 worked fine. As the op said, ie was fine and ff results on speedtest.net were half speed, all over the place, choppy and unreliable. I have just turned protected mode to 0 and it's same as ie now, nice and smooth and 127Mbit down, nice and steady.

Here is a video I found that demonstrates the problem I had.

I have microsoft security essentials. Disabling didn't do anything.

Here is a strange thing though, I was using fraps (screeen recorder) to record what happens when I upgraded flash to a version higher than 11.2 and while fraps is running, the speedtest.net result was fine, just like ie. Exit Fraps and the problem returns. Q) what is Fraps doing to make flash work in protected mode?

How do i disable this please care to explain :p

protected mode to 0 ?

Hi Broken, I thought you already knew how to do this when you replied to madperson. "Well @madperson your trick solved the problem i had for ages... With the flashplayer on ProtectedMode=0 it works like a charm"

To disable Protected Mode, add the following line to your mms.cfg file located in:

Windows 32bit: C:\windows\system32\macromed\flash

Windows 64bit: C:\windows\syswow64\macromed\flash

ProtectedMode=0

Nope didn't know thanks man :)

Btw what i always did was disable hardware acceleration in firefox, doesn't help either though. i'll try your method, thanks.

I have no mms.cfg file in there... Just dll's and uninstallers and plugins.

Create one using notepad. If you can't see file extensions, (i'm using vista)

Start > Settings > Control Panel > Folder Options > View Tab >

Uncheck 'hide extensions for known file types'

Then rename your .txt to .cfg

You edited previous link for the folder Peter cause now i see the textfile, thanks :D