How can it be that this problem only occurs in IE.  It is their technology on their platform!

When using Internet Explorer to browse a page that contains an UpdatePanel, there is a delay (often anywhere between 10 seconds and 45 seconds or more) after clicking a page element that initiates an async postback. The delay is not experienced when using browsers other than Internet Explorer.

FYI,  FireFox’s performance is superior on the same code base in my experiences so far.  I have opened up a case with Microsoft, so we will see what the IE team has to say.  More to come…

http://support.microsoft.com/kb/2000262