High CPU usage/jerky when scrolling a page

[ChristofferS]

Using dapper.

I get very high CPU usage when scrolling pages in firefox. Eg. on osnews.com, the CPU usage goes to almost 100% and the scrolling is very jerky.

[Michiel (fabermichiel)]

I have the same here. When scrolling the ubuntu.com mainpage i get a load of more then 50% up to 99%. And ubuntu.com isn't a big page. If i try osnews.com i also get the high cpu load.

I use breezy with firefox
firefox -v gives: Mozilla Firefox 1.0.7, Copyright (c) 1998 - 2005 mozilla.org

[Sitsofe Wheeler (sitsofe)]

Scrolling is an expensive business (unless all your data is on the video card and you only use video card operations), especially if your window is large. I see the same thing in other browsers (e.g. Opera) so I'm inclined to say that if you move a large window a lot of CPU is going to be used up because the sheer amount of blitting between main memory and video ram going on.

This is more of a x.org issue than a firefox one and even then there are is only so much that can be done unless everything is accelerated...

[David Finch (ubuntu-mytsoftware)]

This and my bug report #32561 might be the same bug. https://launchpad.net/distros/ubuntu/+source/firefox/+bug/32561

I was able to confirm that the problem is pretty specific to Dapper's Firefox 1.5 package by testing Mozilla.org's build of Firefox 1.5 on Dapper and verifying that Mozilla.org's was not sluggish at all in comparison (or in general). And several people replied to my forum post to confirm the unusual slowness. But my bug report is very recent and has received no replies yet.

[ChristofferS (ubuntu-curo)]

I can confirm that Mozilla.com's firefox package (the default linux one that gets offered on the front page) is much faster than the one in Dapper.