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Firefox CPU consumption jumps when mouse moves

New Contributor

Firefox CPU consumption jumps when mouse moves


Whenever I move the mouse in Firefox 18.0.1, the firefox.exe process jumps from 0% to 30% CPU consumption. When other stuff happens that requires CPU resources I experience a drop in responsiveness, so please don't tell me that 30% is acceptable Smiley Wink

I made a default profile to test this. I also disabled plugins and tested in Firefox safe mode. I'm running a 3 days fresh install of Windows 7 64 bit, fully updated. I installed Acronis True Image 2013, if that matters. Firewall and antivirus are disabled. Slowdown occurs even on about:blank pages, however when I'm moving over Firefox options pane, CPU jumps by 10-15% instead of 30%, which I guess is a little more acceptable.

It doesn't happen with Internet Explorer, whether 32 or 64 bit. It doesn't happen with any other program, though few are installed, except a 10-15% increase in Kaspersky Antivirus 2013 UI. I personally don't expect more than 5% increase in CPU consumption when I move the mouse over something. Kaspersky menus are way more animated than Firefox though, so I'm not sure the consumption I report is related to my issue.

My mouse is an EssentielB, model Mulo XL, product code 825258. It's a wired laser USB mouse with 2 extra buttons that do previous/next in Firefox, and 2 other buttons that change mouse speed.

It didn't come with any separate driver, was automatically recognized by Windows and works fine. However I'm using a laptop, and moving the mouse cursor with the touch pad increases CPU consumption by 10-15% instead of 30% with the mouse. (as I said, this is better but still a lot)

Hope you can help! Smiley Happy If you need more info or that I test something, please post here instead of emailing me as I do not check that mail box. Thanks!

EDIT: The troubleshooting information says 0 / 1 window is hardware accelerated, but that's only because Firefox was running in safe mode. In normal mode the problem of course persists yet hardware acceleration works properly.

New Contributor

Re: Firefox CPU consumption jumps when mouse moves

Also, scrolling with the wheel without otherwise moving the mouse uses 40% CPU.

This in on a page with no CSS, no Javascript, no image, nothing but enough basic HTML text to stretch the page vertically so that scrolling up and down is possible.

This ain't right. While I expect scrolling to take more resources than mouse move, it certainly shouldn't need almost half of my CPU, especially when rendering is GPU accelerated. (CPU is Intel Core2Duo P8400, see the system details for my GPU)

Other programs don't do that. Should I post this in bugzilla instead if I want to reach the right people for that issue ?

Thanks Smiley Happy

Note: Scrolling + moving the mouse at the same time don't add up, they take 40-45%. The laptop's touchpad doesn't give better results this time: 40% for scrolling, as opposed to 10-15% for cursor movement.

It sounds like a painting issue more than a mouse one.

Site Moderator

Re: Firefox CPU consumption jumps when mouse moves

Try to disable hardware acceleration in Firefox.

New Contributor

Re: Firefox CPU consumption jumps when mouse moves

I didn't do it previously because I tested in Firefox safe mode, where I think HW acceleration is disabled, and the problem persisted.

Still, I tried your suggestion in normal mode and unfortunately, things did not improve.

Then I tested vertical scrolling with HW acceleration disabled, and it managed to get worse (I didn't test scrolling in safe mode) . From 40% CPU consumption it bumped to 60%; almost 80% with touchpad, possibly because touchpad scrolls faster. In scroll's case, HW acceleration seemed to do its job of improving speed. Still, 40% while being HW accelerated ain't right.

Back to cursor movement, this sounds completely stupid but it seems that when I move the mouse in straight line, CPU consumption is lower than when movement is curvy or circular. Straight I get more like 20%, and 30% with curves. *shrugs*

Also touchpad definitely gives better results for cursor movement, although still higher than expected, so I found a new mouse to test. I used the same USB port and plugged in a Microsoft Wireless Mobile Mouse 3500. I got the same results as with the touchpad, so, while there may be a painting issue, for cursor movement it's about half as bad as expected since there is also a mouse issue with the model I described in first post. But the scrolling is NOT a mouse issue.

(The mouse part of the issue lies in Firefox because other programs don't have that problem.)