Simple jQuery super slow on firefox, IE, super fast on Chrome
<p>Brand new to jQuery. Have implemented the function below into a page I am developing, and what I thought was relatively simple jQuery is proving problematic.</p>

<pre><code>$(document).ready(function(){

    var leftnav = $("#leftnav ul li");

    leftnav.hover(function(){
        $(this).children('ul').stop(true, true).slideDown();

    },function(){
                $(this).children('ul').stop(true, true).slideUp();
    });

});
</code></pre>

<p>Basically, this runs brilliantly in Chrome and Opera - lovely, smooth, fast. In Firefox and IE8 it runs like a dog - jerky, slow, like it's wearing a suit of mud. As I said I am brand new to jQuery - this is the first time I have tried to implement any into a web page. I have tried the same using mouseenter and mouseleave, but there is little difference. </p>

<p>I would have expected problems with IE8, but bit gutted that firefox is giving me issues as I have always sworn by it. Do I just have to accept this and make consessions?</p>

<p>Thanks</p>

<p>EDIT : Ok, I've managed to speed things up a bit. Whilst still not grease lightning Chrome performance, IE8 and firefox are now what I would call acceptable. I got some tips from this excellent page - <a href="http://www.artzstudio.com/2009/04/jquery-performance-rules/" rel="nofollow">http://www.artzstudio.com/2009/04/jquery-performance-rules/</a></p>

<p>I simply made my selector var more specific by giving '#leftnav ul' it's own ID in my markup- #list, and then referencing that in my jQuery code. So,</p>

<pre><code>var leftnav = $("#leftnav ul li");
</code></pre>

<p>becomes:</p>

<pre><code>var leftnavUl = $("#list li");
</code></pre>

<p>From what I gather this allows jQuery to hone in more efficiently on the element in question.</p>

<p>Using console.time in firebug, I have noticed the speed increase from ~15ms to ~10ms for each slideDown operation, just by being more specific in my selectors. </p>

<p>Like I say, not as qucik as Chrome still, but getting better!</p>
