http://www.quirksmode.org/bugreports/archives/safari/index.html "Moving a div with visible scrollbars under any content causes flickering. Easy workaround: apply overflow: hidden; to moving div Firefox specific bug ppknote: Safari is also a bit hesitant, though the bug is different from Mozilla's. Test page http://home.wi.ps.pl/~pmatyjasek/bug1/Test.htm Workaround is included Reported by: Pawel Matyjasek."
I dont see a bug here, closing as worksforme.