Qtwebkit performance issue ???????

I am facing some terrible performance problem with Qt webkit based
application on our board. Indeed I build Qt Demo Browser application for
my board and it has
terrible terrible slow performance. It is highly un responsive, when
scroll using mouse it scrolls very little after almost two min, when I
click on any link
it opens that link after a minute, When I go to some site like
http://cnn.com and do little browsing it crashes. I am running with
directfb support.

i have tested other web kit based small browser sort of application and that works good.
To me it looks like some issue with Qt porting of webkit or in Demo browser
but I have no clue what is causing this problem.

Can any one please point me what should I look for to solve this problem?
any hint will be highly appreciated.