1008560 - Firefox shows 100% CPU usage, severe lag, is sluggish and unresponsive while moving the mouse over a Firefox window on Linux

Status: RESOLVED WORKSFORME

(Firefox :: Untriaged, defect)

Description

[Florian]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:29.0) Gecko/20100101 Firefox/29.0 (Beta/Release)
Build ID: 20140421221237

Steps to reproduce:

For websites: 
Example 1: Open any website, e.g. http://news.google.de and mouve the mouse cursor while trying to scroll using the wheel or arrow keys.

Example 2: Open https://duckduckgo.com/?q=firefox and move the mouse between the results.

Example 3: Open http://demo.phpmyadmin.net/STABLE/?pma_username=root and move the mouse vertically between left navigation pane items.

Please note that it does not matter where exaclty to move the mouse to experience the problem. Though natuarlly the effect will get worse if the mouse moves trigger css/js hover efffects. Please also note that moving the mouse over any non-firefox window has no impact on Firefox performance.


For Firefox window with main navigation enabled: 
Load a few bookmarks, click on "File" and move the mouse to the left and right so that menus start to appear.


Actual results:

Firefox take 80-100% cpu usage and will start to lag, "jump screens" and show sluggishness. This will get worse when you move the mouse faster, to the extent that Firefox will become totally unresponsive until you slow down mouse movement.



Expected results:

Firefox should not use that much CPU time and stay snappy and responsive no matter how fast you move the mouse.

Try all my examples in Google Chrome to see how it should be. You will notice absolutely zero impact on browser responsivness nor snappiness from mouse move there.

Comment 1

[Florian]

Additional information about the system where the bug is always reproducable using _any_ recent linux distribution.

CPU~Quad core Intel Xeon CPU E31230 (-HT-MCP-) clocked at Min:1582.000Mhz Max:1782.000Mhz 

Graphics:  Card: NVIDIA GF114 [GeForce GTX 560 Ti]
           bus-ID: 01:00.0 chip-ID: 10de:1200
           Display Server: X.Org 1.15.1 driver: nvidia
           Resolution: 1600x1200@60.0hz, 1600x1200@60.0hz
           GLX Renderer: GeForce GTX 560 Ti/PCIe/SSE2
           GLX Version: 4.4.0 NVIDIA 331.67 Direct Rendering: Yes

Comment 2

[:Gijs (out for now; he/him)]

This sounds pretty bad. Unfortunately (fortunately?) does not happen to Firefox on every Linux machine. Certainly not on mine. So to figure out what's going on, can you attach the output of the "about:support" page to this bug? (you can copy the "raw data" to the clipboard using the button on the page)

Additionally, could you try if this problem persists if you restart Firefox using the menu item under "Help" entitled "Restart Firefox with add-ons disabled..." ?

Comment 3

[Cornel Ionce [:noni] [Hubs QA]]

Attachment: about:support

Mozilla/5.0 (X11; Linux i686; rv:32.0) Gecko/20100101 Firefox/32.0

Reproducing on Latest Nightly, build ID: 20140512030202, even using Safe Mode.
The CPU usage increased to 50-80%, didn't reach the full usage.
I've attached my about:support details.

Comment 4

[Florian]

Attachment: about:support

Attached about:support as requested.

Problem reproducing in new firefox installation with clean profile. Restarting with disabled addons nor safemode have any positive effect.

However, the described effect is much less noticable if I manually set my cpu clock to the maximum possible (from 1.8GHZ to 3.5GHZ). Especially the "blocking" effect while scrolling (Example 1) is almost gone, Example 2 feels a lot better, but is still noticable, Example 3 feels only little better and can in no way compete to chromes snappiness. 

I also tested on my brand new laptop (Core i7 4600U) and unfortunately can reproduce all 3 Examples.

Overall, it seems that Firefox needs a very beefy CPU to achieve a decent and usable performance under Linux. 

I'm happy to provide more information or make tests if you request so.

Comment 5

[Mats Palmgren (inactive)]

I can't reproduce this bug, in Nightly and FF29 on Linux64.

Comment 6

[Florian]

(In reply to Mats Palmgren (:mats) from comment #5)
> I can't reproduce this bug, in Nightly and FF29 on Linux64.

As I mentioned in my last post, with a very beefy system the bug is a lot less easier to reproduce. And with a polling rate lower than 250Hz the effects are less noticable, too. 

So, could you please attach about:support and the output of `inxi`? What mouse do you use and which polling rate is configured? 

Also, can you verify that your Firefox is actually as snappy as Google Chrome in all examples?

Comment 7

[Mats Palmgren (inactive)]

Firefox Nightly appears as snappy or snappier than Chrome 36 on the first
two links in comment 0.  The third link seems to need authentication to use
so I couldn't test that one.

Comment 8

[Wayne Mery (:wsmwk)]

(In reply to Mats Palmgren (:mats) from comment #7)
> Firefox Nightly appears as snappy or snappier than Chrome 36 on the first
> two links in comment 0.  The third link seems to need authentication to use
> so I couldn't test that one.

Florian, still see this?

Comment 9

[Florian]

I did all 3 examples and with 40.0.3 cannot reproduce any sluggishness nor unresponsivness.I still see a very high CPU-Usage for the firefox process while moving the mouse & scrolling at the same time though this is less of an issue for me right now as it does impact visible performance only to a tiny degree.

So it seems you introduced a fix for this specific bug somwhere between 29 and latest stable. Thanks for that.