Although we can defined
$('ul').superfish({ speed: 0 }); to make it feels like it has no opacity animation, there is still opacity animation (it's just become very fast so you don't notice). Therefore in IE7/8 the font smoothing issue occurs. In IE7, font loose ClearType completely; in IE8, font loose ClearType during the animation. Take a look at
the official demo on IE7/8.
How can we disable opacity animation for IE7/8?