Ah ha. I bet I know why. IE has a nasty tendency to match the end of a multiline html comment using non-greedy regular expressions. This is a flaw. Yield build was turned off with multiline comments. See:
Code:
<!-- Yieldbuild OFF
<!-- GOOGLE AdSense / Yieldbuild -->
<center>
<!-- YB: nav (728x15) -->
<script type="text/javascript"><!--
yieldbuild_client = 779;
yieldbuild_layout = "thread___universal_zones";
yieldbuild_loc = "nav";
yieldbuild_options = {};
//--></script>
<script type="text/javascript" src="http://yieldbuild.com/s_ad.js"></script>
</center>
-->
IE should ignore everything up to the green --> tag, but instead it only seems to ignore to the red --> tag.
I'm going to make a mirror of the page and I need an IE user to click it and tell me if it's still slow.
You know what? I'm pretty sure I'm wrong. I think IE just doesn't handle the fact that yieldbuild is broken as gracefully. Non-greedy is logically the best pattern search. Woody probably just didn't realize what he was doing was wrong
EDIT2: nope. It's not standardized properly in IE.