Scroll Lag with CSS3 box-shadow property?

Question

I added a box-shadow to a section of a page recently to give it the same shadow border effect that is seen on Mac OS X apps. It looked great, but I noticed that

Answer 1

#shadow {
-moz-border-image: url(img.png) 10 / 10px; #Firefox under v15.0#
-webkit-border-image: url(img.png) 10 / 10px; #Safari, Chrome under v15.0, Android & iOS#
-o-border-image: url(img.png) 10 / 10px; #Opera under v15.0#
border-image: url(img.png) 10 / 10px; #IE v11+, other new Browser#
}

Cross browser version for old and new browser. Simple img: http://i28.tinypic.com/2njzkt1.png

style :fixed for images too overload perfomance browser