How to reduce load when fading in multiple elements in jQuery
for optimizing this function - will be better if you'll give an example of working code. Just upload some sample to http://jsfiddle.net/.

Anyway, to reduce the load on any animations, use default CSS transitions.

-moz-transition: all 0.5s ease-out;
-o-transition: all 0.5s ease-out;
-webkit-transition: all 0.5s ease-out;
transition: all 0.5s ease-out;


And then change the opacity from 1 to 0 or change class. Here is an working example http://jsfiddle.net/x6fxx/ , works much faster then jquery's script, this one is css based solution which is using hardware acceleration ( modern browsers ).