The http://webtretho.com website flash component(plugin-container) to consume 100% CPU causing firefox to hang. Reproducible on Firefox Nightly and Firefox Stable on Ubuntu 10.04.4 LTS using adobe-flash plugin package version 188.8.131.52-0lucid1
The one flash component (a timeline, right?) on that page works fine here, FF 11.0 on Fedora 16 with flash-plugin-184.108.40.206-release.i386.
Andre, if you browser other pages in this website. There are other flash ads that cause this problem.
arky: Then please isolate a concrete testcase in order to reproduce this, otherwise there is nothing to fix...
I can't reproduce with Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:16.0) Gecko/16.0 Firefox/16.0 0624 build. Although initial page load stinks. given your other bug 751530 I suspect something is goofy on your system. It would probably be good to file such bugs as unconfirmed.