How to avoid page flickering (asp.net C# web application)

Hi all,
how to avoid the flick of page during postbacks.  I am using master page and some 20 pages.. 
i tried with this pasting in master page.. but still page flickers..
<meta http-equiv="Page-Enter" content="Alpha(opacity=100)"> and
<META http-equiv="Page-Enter" content="blendTrans(Duration=0.2)"> <META http-equiv="Page-Exit" content="blendTrans(Duration=0.2)">
pls help how to do..
Thank you..