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Firefox mouse-over lag analyzed and workaround

Hello everyone!

Since it is not possible to create tickets without a premium account I am trying to get my information through here. Others have reported it before and I am experiencing the same issue: doing moving the mouse-pointer over a JWPlayer embedded video leads to serious lag and video dropouts (not audio). This does not happen with other Flash or HTML5 based players on this system, including both variants of Youtube.


The issue is *not* a direct problem of hovering the mouse over the player, it is a problem of the mouse-pointer being redrawn as a hand symbol when Firefox is having active focus (being the active foreground window). This means that there is no lag when Firefox is not having active focus, even though the player bar still pops up with mouse-overs.

Lag/dropouts only happen once the Firefox window becomes the active foreground window, because then the mouse-pointer also changes to a hand symbol. The drawing of said hand shaped pointer seems to be what causes all the troubles. The severity varies with various web-sites, but one where can bring Firefox almost to a stop (and corresponding "want to stop scrip" message) is:

It's noteworthy that the longer you move the mouse-pointer over the video the longer it takes for Firefox to return to normal. And in the case of the linked site you can even see the mouse-pointer blinking on and off slowly as it seems to be redrawn.

None of the following measures helps to alleviate the problem:

- Turning off/on hardware acceleration for mouse-pointer drawing.
- Turning off/on hardware acceleration in Firefox.
- Using Adobe Flash uninstall tool to do a clean reinstallation of flash.
- Making sure that the GPU (AMD 6750M) is clocked to maximum clock speed and utilized.

It does not happen when the video is played back in fullscreen-mode, though, only when it's embedded/windowed on the site.


Turning off Adobe Flash Protected Mode!

Obviously that workaround cannot be the real solution, which is why I provided all the information here.


3 Community Answers

Timur Born

0 rated :

Here is more information:

All of the above was tested on my first system:

Windows 8.1
AMD driver version (2013)
Firefox 42

Now I got some different results on a second system:

Windows 7
NVidia driver version 361.43
Firefox 44.0.2

First of all, the Adobe Flash protection mode workaround does *not* work on the second system!

Furthermore on this system I am using a Logitech mouse that allows me to switch poll rate via profiles. At 125 Hz no video lag happens upon mouse-over! At 500 Hz lag happens, but the time for Firefox to get back to normal is relatively short (pointer keeps blinking quickly on the web-site linked above). At 1000 Hz Firefox comes to a complete halt and the mouse-pointer keeps blinking (quickly) all the time.

Using the very same mouse and driver on the first system also leads to video lag at 1000 Hz even while Adobe Flash protection mode is off. BUT (!) with protection mode off it only happens at 1000 Hz and does not keep stalling and blinking once the mouse-pointer is removed from the video. AND with protection mode on (!) it is worse at 125 and 500 Hz with long pointer blinking afterwards, but better at 1000 Hz with pointer blinking quickly and short once the pointer leaves the video area.


JW Player Support Agent  
0 rated :

Hi, Timur.

My name is Alex and I am one of the Support Engineers at JW Player. I will be more than happy to assist you with your questions.

Have you experienced the same issue with JW Player 7? We have JW 7 player on our Stream Tester that you can test with.

Thank you.

Timur Born

0 rated :

Hi Alex,

thanks for getting back to me. I am just an end-user browsing sites that make use of JWPlayer. One site using JWplayer 7.1.4 is, the problem remains, albeit less bad than on the arabian tv website I linked to before.

When I noticed the seriously laggy experience with these sites compared to how other embedded video works flawless I digged deeper and thought to report it here and on the Firefox Bugzilla site.

Here is the related old Bugzilla thread about how mouse-over affects video playback negatively in Firefox:

Here is an old JWPlayer question that seems to describe something similar:

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