** some improvements coming
* Image animation now controlled by refresh driver; should improve performance substantially on pages with lots of animated images, especially in background tabs (Scott Johnson) {{bug|666446}}
* Major ancient table-related bugs fixed (table margin collapsing, use of relatively positioned tables as containing blocks for absolutely positioned descendants) (ehsan) {{bug|10209}}, [http://ehsanakhgari.org/blog/2011-10-04/upcoming-changes-absolute-positioning-tables-and-table-margin-collapsing-firefox-10 blog post]
= Video =