I've been working on a site which makes heavy use of JQuery and it was all going very nicely until we started testing in IE6+7. The performance of the site was dreadful.

After doing some digging around, I noticed that one method was being called x,000 times and resulted in a 7000ms process time. The method in question was "doScrollCheck".

Making the following code change (commenting out several lines):

// ensure firing before onload,
// maybe late but safe also for iframes
//document.attachEvent("onreadystatechange", DOMContentLoaded);
// A fallback to window.onload, that will always work
window.attachEvent("onload", jQuery.ready);
// If IE and not a frame
// continually check to see if the document is ready
//	var toplevel = false;
//	try
//	{
//	  toplevel = window.frameElement == null;
//	} catch (e) { }
//	if (document.documentElement.doScroll && toplevel)
//	{
//	doScrollCheck();
//	}

I was able to take the time from 7000ms all the way down to 720ms.

Whilst I appreciate that the code I have commented out is relevant, it does have a huge performance hit.

Is there any way that the above code could be re-factored to perhaps, reduce the timeout interval from 1ms to something greater? Only perform the doScrollCheck code if the page actually has iframes in it? Some other creative method that does it all far better.

Cheers,