ah I found the answer by checking what Techcrunch / AOL does.
You load the XFBML as the user scrolls.
1.) Don't Parse XFBML on FB.init or the loading of the JS SDK
FB.init({
appId : APP_ID,
xfbml : false
});
2.) Load jQuery and jquery.sonar.js - this contains scroll and scrollout custom events
<script src="//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<script src="http://artzstudio.com/files/jquery-boston-2010/jquery.sonar/jquery.sonar.js"></script>
3.) jQuery code to parse XFBML on scrollin event (stolen from Techcrunch)
jQuery(document).ready(function($) {
var $shareWidgets = $( '.share-widget' );
$shareWidgets.bind( 'scrollin', { distance: 500 }, function() {
var $share = $( this );
if (!$share.data( 'initFB' ) && window.FB) {
$share.data('initFB', 1);
$share.unbind( 'scrollin' );
FB.XFBML.parse( $share[0] );
}
});
});
4.) wrap your XFBML tags in a class called 'share-widget'
<span class="share-widget"><fb:like></fb:like></span>
and voila! no more dang XFBML slowing down your pages. Ofcourse this only helps when you have a lot of XFBML tags on your page. Which most blogs may have.
Thank you AOL!
See the SlideShare presentation of AOL using jQuery: http://www.slideshare.net/daveartz/jquery-in-the-aol-enterprise where they talk about this and other optimizations they use.