User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.9.1.5) Gecko/20091102 Firefox/3.5.5 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.9.1.5) Gecko/20091102 Firefox/3.5.5 Scrolling is slow. Hiding the anchor located by $("fdbk_tab") causes scrolling to go to normal speed. Reproducible: Always Steps to Reproduce: 1.visit url 2.scroll --> slow 3.javascript:$("fdbk_tab").hide();undef 4.scroll --> smooth Actual Results: firefox.exe hogs a processor core while I scroll. Expected Results: Don't use so much processor :) * No plugins enabled * Happens both with and without smooth scrolling * Core2 6700 @ 2.66GHz, 4GB RAM

Hello! I experience this bug too. 1. Visit this url: http://client.starchat.ee/987hjky4/thus.html 2. Click on button "Save". No matter which one. 3. You will see that div box on left bottom corner appears. While it is there try to scroll the page - you will notice that page lags when you scroll it while the div is visible on bottom left corner. After it is gone, the scrolling is working smooth without any problems.

Forgot to mention: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.7) Gecko/20091221 Firefox/3.5.7 (.NET CLR 3.5.30729)

Check also bug 90198 attachment 90636 [details]. And compare the cpu usage with attachment 90639 [details]. Reproduced with latest trunk.

https://bug90198.bugzilla.mozilla.org/attachment.cgi?id=90636 doesn't use position:fixed. Paint flashing shows that we don't do unnecessary repainting while scrolling http://www.flightcaster.com/faq. http://client.starchat.ee/987hjky4/thus.html is gone.

This is still an issue for me. Specifically, at lucidpress.com, when editing a document if I add a scrolling area and then double click on that scrolling area, then scrolling is painfully slow. In this case there are multiple elements with position:fixed, as well as multiple canvases. (one of which is position:fixed). Disabling smooth scrolling in the preferences fixes the problem, however, I can't really require all of our users to disable smooth scrolling on their browsers. This is only a problem on Firefox.