743302 - High cpu usage when loading flash video

Status: RESOLVED INCOMPLETE

(Firefox :: Untriaged, defect)

Description

[Dub]

User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:11.0) Gecko/20100101 Firefox/11.0
Build ID: 20120312181643

Steps to reproduce:

I watch movies on Youtube or other video sites.


Actual results:

While loading, the cpu usage of the process "firefox.exe" is very high (full core usage, ie 25% on my 4-core machine).

It makes the video very laggy while still loading.

Once fully loaded, the reste of the video plays smoothly again (CPU usage back to normal)


Expected results:

Flash videos should not be impacted by Firefox CPU usage of downloading.

Comment 1

[Matthias Versen [:Matti]]

What is your connection speed ?
Can you reproduce this in the Firefox safemode ?
http://support.mozilla.org/en-US/kb/Safe+Mode

Comment 2

[Dub]

Sorry, i gave too few details:

My connection is a fast DSL (20Mb/s). I never had this problem before, it only happens for some weeks (months maybe). I cannot figure out when it changed.

Also, it's not due to the loading being too slow : the "load bar" increases much faster than the "read bar", and it keeps happening even when 20 minutes out of 21 are loaded, while still only playing the first minute.

One last thing: if the server's bandwith is slow, it's not happening. It looks like only high downlaod rates overload the CPU.

In short: when the video cache of a flash movie is loading at fast speed, firefox gets laggy (the whole firefox process).

Safe mode: it disappears indeed in safe mode. I'm going to try to find the guilty addon.

Comment 3

[Wayne Mery (:wsmwk)]

URL ?

Comment 4

[Phoenix]

Resolved per whiteboard