User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.3) Gecko/20070309 Firefox/2.0.0.3 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.3) Gecko/20070309 Firefox/2.0.0.3 For some web pages firefox uses 99% of CPU. for example http://news.softpedia.com/ I tried this site with IE7 & Opera, the result was normal, they are working with zero CPU. Reproducible: Always Steps to Reproduce: 1.Open the firefox. 2.type the site- http://news.softpedia.com/ 3.Check the CPU uses. Actual Results: CPU uses more than 80%, sometime 99%. Expected Results: CPU uses must be zero percent after opening the webpage.

Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9a5pre) Gecko/20070509 Minefield/3.0a5pre This is even more a problem on trunk. In trunk it even hangs (can't close Firefox when I want). Regression range for trunk is http://bonsai.mozilla.org/cvsquery.cgi?module=PhoenixTinderbox&date=explicit&mindate=2006-08-18+15%3A00&maxdate=2006-08-19+04%3A00 but it is a slight difference. The second time you load the page it sometimes doesn't hang.

Confirmed on Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9a5pre) Gecko/20070509 Minefield/3.0a5pre Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.1.4) Gecko/20070509 Firefox/2.0.0.4

confirmed using: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9a6pre) Gecko/20070626 Firefox/2.0.0.1 ID:2007062604 It is caused by the News Ticker (http://news.softpedia.com/js/scroller.js). Preventing loading this Script (e.g. with an Adblocker) circumvents the high CPU-Usage. Since the Script claims to be "Use Freely as long as following disclaimer is intact" i've attached it. Perhaps a Dev wants to have a quick look at it :-)

Same problem is present in: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9b5pre) Gecko/2008030405 Minefield/3.0b5pre CPU usage goes to 50% on my hyper-threaded cpu.